Did Roth in 2015 and 2016, signed up for 2018. Would love to hear from those that have finished on the old and new run course, how much slower, if any, the new course is?
Tom, Add me to that list. Do you happen to have the computrainer file for the new course?
The new course is much more varied. Pavement for ~1k then dirt path for 1k then pavement for 2k then crushed gravel path along canal for ~1km to turnaround. Same pattern back to town crushed gravel-pavement-dirt path-pavement. Then it’s 5.5km in the other direction with several rolling hills and cobbled sections before the run around the lake to turn around in Buchenback (spelling).
The new course keeps things interesting and there always seemed to be a ton of spectators, but the hills and varied surfaces make it tougher to get into a rhythm. I would say the new course is 5-10minutes slower depending on your innate running ability. A 3:00 Ironman marathon on the old course would likely be 3:03-3:05 on the new course and a 4:00 run would be closer to 4:07-4:10 in my guesstimation
Although I never did the old course, at one point this year as I was shuffling the last couple of miles, an older guy ran with me for a few moments and, competely unsolicited, mentioned to me how “this new course is a lot harder than the old course”.
All I know is that there were two miles of continuous gradual uphill which we had to run twice.
It didn’t really matter to me as I pretty much knew my race was over from the very first pedal stroke of the bike. I spent over 10 hours wanting so badly to drop out. Making myself even start that marathon was one of the hardest things I’ve ever done.
with several rolling hills
I probably would not call the section up to Buechenbach a rolling hill but, for a run course, a serious climb (~2km long, 2~4% grade) 
The new course has pros and cons compared to the old course (I raced both), from my pov definitively more pros. Only con, in case you would come to chase your PR, it is definitively slower. And I do not believe that we will see a new world “record” in Roth again any time soon (unless they make it even shorter than 41,5km ;-)). As stated by Seth, something between 5~10 min. slower sounds realistic to me. you definitively need to get your pacing right. Do not burn any matches on the first lap’s climb, otherwise you might end up walking up the little hill on the second lap, at latest. Should you run in the flat 5:00min/km, expect 5:30~6:00 on the way up.
Others might mention cobblestone section as con, but there so may spectators around that section that you probably do not even notice.
Pros:
You are not left alone at the canal. There are spectators almost along the full run course. Mentally, so much easier. Just run 5km out, turn around, same way back. Same thing the other way round. Then do it again and you are already done. Much more shade. Easy for your family and friends to see several times (if you should not be travelling alone). They can simply rest at one spot and see you four times. This is the big winner for me.The turnaround in Buechenbach is spectacular. And once you are there on the second loop, you are more or less done. Just get down the hill, through the city center and to the finish line. Not sure how it compares to previous years, I cannot remember exactly, but it feels like there is an aid station every km. In fact, there are 24 aid stations if I am not wrong. More than enough.You can follow the Pro race while the overtake you on their second loop or while they run towards you.
Some might argue that it gets packed on the course and through the aid stations - I have not had an issue with that. And some argue that the “good, old spirit” at the canal gets lost - not sure what that spirit was, I hated running along the canal Or the climb would be too tough - ok, go and do a sprint if tough is not yours…