Yep, very familiar with UCAN, ‘LIVSTEADY’, formerly ‘super-starch.’
I got a little long-winded here because I know you’re a cardiologist and probably don’t mind a few details. I have appreciated your very thoughtful responses on the forum. I suspect a few other folks might find my commentary helpful here, so here goes.
You’ll be able to manage a higher carb intake rate with less risk of GI issues if you use something non-starch-based, no matter how science-y the starch is. Folks generally end up using UCAN because they’ve had a bad experience with up and down energy in training and racing. It’s been a phenomenal marketing strategy for UCAN and kudos on the marketing execution. Nothing but respect for that marketing team. Truly. They have really cornered a good chunk of the market that grew tired of the fluctuating energy levels common to all of us.
The same problem can be solved by increasing fuel intake rates with a combination of glucose and fructose, also known as “multiple transportable carbohydrates.” This has been known since at least as far back as 2000, and probably earlier, but I didn’t dig up anything earlier. The issue with the multiple transportable carbohydrate approach has always been that folks believed there were relatively low limits on total hourly carb intake rates. These beliefs mean folks don’t consume enough of the fast stuff. These beliefs in low hourly carb limits have caused lots of folks to experience the up and down energy because they’re only giving themselves little bursts of sugar here and there, when they’re burning through it by the truckload. Instead of changing fuel sources to a slower-absorbing fuel source, it’s best to consume more of the faster stuff. If you use slower-absorbing carbs, GI distress is more likely, when fueling anywhere near the known optimal carb intake rates (70-130g/hr for most people for events over three hours).
When moving from slower absorption to faster absorption sugar sources, plan to consume more of them per hour. And plan to stay well-hydrated, too. Don’t just chow down on a gel or two, without water, and hope for the best! GI issues are the first thing people experience when they make the move from UCAN to something faster, at a higher quantity. Hydration is almost always the cause of those carb-triggered GI issues.
Here’s the breakdown of the common paths I see a huge swath of consumers in the endurance nutrition market take:
Path 1: Fuel randomly. Bonk and feel terrible. Need more fuel. Consume more fuel. Get GI issues. Reduce intake rate. Feel up and down energy. Turn to something like UCAN, keto, EFS, or some other method that promotes (advertises) a more sustained, less up and down energy feel. Then they keep their fuel intake rate below what would be optimal for them, because all of those methods recommend the bottom end of optimality, at most, for carb intake rates.
Path 2: Fuel randomly. Bonk and feel terrible. Need more fuel. Consume more fuel. Get GI issues. Switch fuel source. Read lots about fueling steadily. Learn about multiple transportable carbs (glucose & fructose). Settle into a fueling practice that kinda works. Train hard. Get fitter. Still notice that there are still ups and downs in energy, even though they’re consuming 70-90g of carbs per hour. Start reading about fat oxidation and its importance. Start thinking about doing some training fasted. Read about carb periodization. Start experimenting with limited fuel intake on some rides so that you’ve got the fat burning ability you need to tough out those little lows in energy you get at 80g/hr carb intakes. Most people stop here and believe this is the way, for years. Your fitness powers you through, and you do have some fat burning adaptation from carb restriction and from simply being tough as nails and training hard.
Path 3: is really just an extension of path 2. Path 3 looks like, you’ve been carb fueling for years and it’s been working pretty well and you’re tough and fit enough to tough out the little dips in energy during racing, and that’s just endurance training and racing to you. But now you’ve read a little bit about how if you adapt to fat burning by carb restricting during some of your training, your body gives up a greater amount of carb burning ability than it gains in fat burning ability and that doesn’t feel like a good thing. You’ve read the papers from the last 5-8 years that are pointing to the fact that any carb restriction during training may hinder carb oxidation ability to a greater extent than it helps fat oxidation ability, and that any gains in fat oxidation might be shorter-lived than the losses in carb-burning ability.
UCAN and other “slow / steady” carb sources market to Path 1. Keto products and systems market to folks in Path 1, too. And it can work. Just not quite as well as really getting it right with good carb fueling paired with good hydration. Most of the rest of the nutrition product market currently advertises to Path 2. Their marketing teams have to dream up endless creative ways to differentiate themselves from the market leader: Gatorade. Thankfully, Gatorade has been thoroughly vilified because people mismanage their hydration often enough to have gut issues with it, or they under-dose it completely and have up and down energy. This mismanagement of hydration and dosing, resulting in folks disparaging Gatorade (not to mention the strong flavor and high sweetness of their products) has given smaller companies wiggle room to get a foothold in the market, thankfully. Gatorade still makes ~50% of endurance fuel and hydration revenue, annually, while everyone else dukes it out for table scraps. Unfortunately, these smaller companies sell premium priced products and they’re already scratching their heads on how to market to the folks who are slowly migrating from Path 1 and Path 2, to Path 3. People are starting to understand that they’ll benefit from higher fuel intakes sometimes. It’s starting to require spending an arm and a leg on something that folks are realizing they can make at home with stuff they’ve got in their kitchen already.
Hope that was insightful. Feel free to ask any questions. Apologies for huge blocks of text, meandering thoughts, and typos. I didn’t go back and edit much. 
