I own a refurbished lifefitness 9100HR model, this model although limits my run upto 10mph, but never had any problems with the machine. Feels solid at top speed (10mph) even with 4 degree inclination. This treadmill is very very old but still able to deliver smooth performance.
I used to travel a lot, I found most of the gym either use technogym or lifefitness products. I want to upgrade to my next treadmill that will either be a lifefitness T95i or technogym runrace( If I could find a seller).