there are plenty of car simulators out there - would you buy a car based on that or would you rather take it for a test drive?
 
many retailers allow for a 30 day money back which is usually enough to see if the interface is what you need/want and stable enough ...

Cactus Music
Or buy a Mac  :) 

Recent Mac OSX updates haven't been exactly super smooth...   
El Capitan had some major teething issues.

I usually buy gear that I'm unsure of from retailers with great return policies.  I've made great use out of Amazon's return policies and I've heard good things about Sweetwater's but haven't needed it for anything I've ordered from them.   Worst case scenario assuming you treat the gear right is you end up paying for shipping costs.  Much better than being stuck with a $500 brick.  
 
My favorite is Amazon's Christmas return window.  You buy something starting November 1 and you can return it up to any point before January 31.  I find that life often gets in the way of the usual 30 day return policies so this works out great.
 
I've also negotiated custom return policies with manufacturers in the past.  I wanted to try out a pricey delay pedal from a high-end guitar effect manufacturer but at the time you could pretty much only order direct from them and they had no return policy other than for defects.  I emailed them asking if they could make an exception and they agreed to a two-week, no-questions-asked trial period (which was unnecessary because the pedal turned out awesome).  

Buy to try is OK..but...wouldn't it at the very least be SO cool to have test results of all the important parameters for an interface, particularly latency beforehand for comparisons sake if nothing else? Like, I'm considering the new UA Twin, the new 6/8 Presonus box, those latest Behringer interfaces (real darkhorse!) ..maybe a Focusrite box of some kind...how cool would it be to run tests on all of them to know which has the lowest latency (among other parameters)  in MY computer? Too awesome.

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rsinger
... a thread about audio interfaces. It would make sense to do something similar in the top part of this forum so it would be sticky. People could post what interface they are using, if it is stable, what buffer sizes they are using for tracking/mixing and what OS they are using.
 
Just because some one posts that they have an I/F that is stable and low latency doesn't mean that another person with a different system that is unstable won't have problems, but at least you know the drivers are good.

+1 and great suggestion. Given the endless configuration variations this should be useful for many users.