Nancy: I have at least 20 Icelandic riders I have sold Sensations to in the past 2 years that are close to your weight. Many ride longer distances. With appropriate padding, they seem to do quite well. If you want to contact me off list perhaps a few of them would be willing to speak with you about their experiences. I know Susan Cooper rides her TWH in a Sensation /is about your weight & does distance riding as well. Maybe she can weigh in on her experiences.
I too was skeptical about "treeless", but the Sensation really does offer better weight distribution because of the interior construction & multi point rigging that most other treeless saddles & believe me, I have tried them all both with myself & my group of 30 riders out here. There are even several equine chiropractors that rec. the Sensation for appropriately built horses with riders under 200lbs. Kaaren