[long winded anecdote]
Last year the LBS had a few Trek Madone 6.5 demo bikes. I have a 2004 Madone SL 5.9, so was interested to compare. New ones were Ultegra Di2, Race X Lite wheels, Bonty finishing kit. Mine is Dura Ace 7800, older Race X Lite wheels, Bonty finishing kit.
Collected demo bike, took home, set it up, geometry was a bit different - more relaxed, but I'll forgive that. Rode 100 miles the next day, loved it, super comfy, felt light, fast, really nice. Would've bought one there and then.
Fast forward a week and they still had them, so I rode to the shop on my Madone, and jumped straight on the same demo bike. Hadn't been used in the interim, so still set up for me. Doing the straight back to back made me realise that actually it didn't feel as nice as mine. Yes the Di2 was cool, and it did handle marginally better, but actually it was a good chunk heavier and didn't climb as well as mine.
The lure of 'shiny thing' on the first demo ride (and actually my assumption that it would be abjectly 'better') definitely blinkered me, so potentially had I bought after a quick test ride I'd have made a mistake.
[/long winded anecdote]
Bought last couple of bikes with no test ride. Bought my Superfly without ever really riding a 29er full stop. I'm less fussy than many though, will generally make things work. Plus it was a bit of a fait accompli as they didn't do any 26" wheeled XC bikes.