Ya got me on that.
I don't have any experience with grip shifters. The old school thumb shifters (Deore SIS) have been my main types. These can be set to both friction and index modes in about a second. Other types I've used have been bar end shifters, which work the same way - also, no problems. Right now I have two road bikes with brifter types. One has all Shimano 105 (mid-price, very good stuff) and the other is an older 1995 roadie with entry-level Shimano RSX which was much like 105 except it was for 7 speed bikes. Both work flawlessly.

By "trigger shift" do you mean Rapid Fire? Very common, and it comes in various price grades like all the others mentioned. I don't knoew the actual mechanics involved, but Rapid Fire performs like brifters.

EDIT: Here's a site that has Shimano shift systems listed by hierachy. http://mc2.vicnet.net.au/home/vichpv...manoparts.html

There's alot of grip shifts around. It's probably fine.