OK, a couple of reality checks:
Most all coaches will handle well under ideal conditions. It is in cross winds, bad road surfaces, etc where the "men are separated from the boys". These adverse conditions are obliviously difficult to plan on a test drive. Did that with a sailboat we were considering for off shore work once-- waited until it was blowing 30+ to go for a test sail.
You likely have no idea if the coach is properly set up. Tire pressure could be off by 30 PSI or even have a flat rear tire. Couple of sales people have been very weirded out when I check tires on a coach before a test drive. But you could rule out a coach for nothing more than improper tire pressure. OR if tire pressure is well on the low side, could think it rides really well (soft ride) and it won't ride nearly as well when tires are properly inflated.
Weight distribution is very unlikely to be the same empty on a test drive as it is once you have loaded it. Particularly important for leaf spring and torsilastic suspension coaches. Add 80 gallons of water, mostly on the front axle and a rough ride all of a sudden smooths out.
Reality, much of any test drive is YOU becoming accustomed to the coach rather than a reasonable evaluation of the coach's abilities.
In all my years of RVing, I have had only one opportunity to to a qualified hands on comparison of different coaches on our short list. It was at an FMCA Convention in Redmond, Oregon. I laid out a demo route that included a narrow back road with lots of curves and uneven road surface. Drove our coach on it one afternoon (the wind blew strongly each afternoon that week). Then on successive afternoons (as close to the same conditions as we could get), we test drove the other coaches on our short list. Dianne made notes on our ride and handling comments. VERY worthwhile, but very difficult to implement.
I am NOT suggesting that you don't do a test drive-- but be aware of their limitations.
