I feel nervous doing the Coke can shim on 25.4 bars and a proper shim would cost about the same as some cheap used risers anyway. Also, I'd like to be able to throw my Turbocat headlight on there every once in a while and it's set up to be mounted next to the stem on a 26.0 clamp.

I don't think anyone makes a 26.0 riser. Get a new stem if you're really antagonistic to the coke can shim. BTW, yesterday I rode around with a 25.4 bar shimmed to a 26 stem with a long narrow slip of paper... no problem.
I find it hard to believe that the light would "notice" the 0.6mm difference.

trust the beer can. itll be fine.

The light has a CNCed clamp, not an adjustable band. The light would probably be easy enough to shim with a piece of rubber but that's one more thing to keep track of.

I definitely don't want to get a new stem because I want to run the 26.0 Salsa I already have. If enough people chime in that Coke can shim is safe I'll give it a shot.

aluminum can works ok on some bars, quite a bit worse on others.. you might want to look into a "real" shim, a la the nitto shim if the can doesn't work out and you still don't want to switch stems - https://cgi.ebay.com/Nitto-Handlebar-...QQcmdZViewItem

When the risers are too small, you must shim it. Shim it good.

Buy some material at the hardware store. flashing? Its gotta be cheaper than the nitto shim. Isnt it like 10 bux?