Sole F80 is a good, tested, proven model with excellent customer service. Not many bells and whistles, but it does the job, and does it well, for a very reasonable price ($1500-$1800).
You do NOT need a commercial TM. If you are strong enough to wear out the motor on your SoleF80, they will replace it free. (I’ve never heard of anyone doing this, even on other TMs.)
Don’t fall in the the horsepower sales trap - horsepower measurements are notoriously inaccurate on TMs, and it doesn’t even matter if you’ve got awesome HP but other critical portions of the TM fail first. As long as your TM has a lifetime motor warrantee (most do at $1500+, as does the Sole F80), you don’t have to worry about killing your TM engine because you’re such an awesome runner.
Some people rightly swear by the better ride quality of their commercial or pricier TMs, and I’m sure they’re right for their purposes, but it’s not necessary, and you’ll def pay a huge premium for some of this ride quality. The SoleF80 runs perfectly fine and smooth, goes 12mph and 15% incline.
I would consider the customer service in purchasing a TM. If anything does go wrong later, you will rely on them for help. And given the moving parts and impact a TM takes in use, in the long run, you may need them. (I had to replace a mildly cracked deck on my Sole F80 - it probably wasn’t necessary, but I asked them about a ridge I was feeling on the deck, and they sent me a replacement for free, no questions asked.)
I wouldn’t spend money on i-fit right now. Maybe it’s improved, but I haven’t heard ANY positive feedback about it despite asking repeatedly about it for years on the forums and hearing from many users.
Also, you might want to consider not spending the money for that fancy color viewscreen, and instead, spending $350 total for a dedicated 32" TV for your TM and a nice metal sturdy tripod stand for it and bluetooth headphones (you can get all on Amazon easily.) I just updated my TM with this setup, and it’s awesome for media viewing even when suffering through a tough TM run. A 7" screen is just sad in comparison, and probably costs a lot more when built in to the TM.
I agree completely with all the comments above. I own a Sole F80 and it is more than enough treadmill. I do about 3-4 hrs of running on the treadmill during the winter and thus far it has been great. My only complaint is that it is a bit loud. I also think that you should spend on other “pain cave” technology like TV’s and computers rather than looking for these on the tradmill. I have a 37" flat screen hooked up to Direct TV, Google Chrome, Blu-ray, Netflix, etc. I can find any and all means of entertainment while running and I stream the Sufferfest videos while on the bike trainer. These are much better entertainment/traning options than a 7" crappy monitor at a bad angle on your treadmill.