... I don't have any personal feedback for you, BUT, ... You can try your favorite WEB Search Engine and enter in, +"tankless" & +"100,000" & +btu, for your search.
If you don't have a 'favorite search engine', I use Alta-Vista, using the aforementioned Search String (exactly as typed). You'll get about 15-20 'hits' with a variety of info. It's a mix of personal comments and 'sales' info. Just another way to get more info on this subject.
If you still want more info and this Forum or the WEB isn't giving you much help, try Plumber's Advice Forum, and post this same question there. I've 'listened' on that forum and have read some good threads on Tankless Water Heaters. Best of luck and hope this helps.