I like the idea of a doing the smash to get an idea of the taste profile of a specific hop you are interested in. I never seem to get around to doing smash's and there are so many hop varities that it would take a lot of smash's to hit them all.
From what I have found columbus, centennial, & cascade all have similar profiles.
Amarillo & Simcoe are pretty disctinct.
If you do the SMASH make sure to use a good amount of hops (I would 5 ounces or so) and load up the back end (20 mins and later) to really draw out the flavor.
If you do a 2-row smash and go light on the hops (basic 60 minute addition + a few quarter ounces throughout the rest of the boil) you will end up with something BMC'ish tasting and I don't think you will really accomplish what you set out to do which is taste the flavor that particular hop contributes.