100mm 2.8 macro L or no?

I just purchased the non-L version because I happen to have about $400 in Amazon gift cards (combination of christmas/birthday/selling back textbooks) so it only cost me about $375 total but I also purchased a 430exII flash along with the lens.

I would have loved to have gotten the L but as much as I wanted it I couldn't justify spending an extra $400 on pretty much just IS and a better build quality. However I'm also probably not going to use it much as a walk around lens.

If I had the extra money to spend, I would have gotten the L though. IS would have been very nice to have.