I've been using a Terry fly ti hollow rails since 2005. The saddle wore out before the rails (partially due to a tear on the side, bike fell over). I'm on a second one since 2010.

I'm your weight and have had no problems.

Strange thing though. Gina is far less than I am but her cromo tubes on a Specialized saddle broke! ....Maybe it was a mfg defect and it seemed to break right at the bend near the rear of the rail. I took it back to the dealer and they replaced it no questions asked, no receipt, nothing, just took it back and handed us a new one while saying "that shouldn't have happened. The saddle was a year old