Lately I've been throwing a Gateway Speed Demon with pretty good results. Never thrown a disc so overstable and I've thrown pletty of overstable discs. It's like a saw blade thrown off the machine. Gateway Spirits are nice as well.
Very fast and the disc is always going to do the full roll over in the air like you want. It was so overstable when I first started using it for thumbers once it rolled once in the air it went straight down to the ground. Now it's beat a little, it gives a nice flowing single roll in the air.
Flick is probably still my favorite thumber disc, it always has as long or longer thumber distance and always know where its gonna land.
I can't really throw the thumber just yet ( haven't figured out the release) but I love throwing tomahawks on a few of the holes I frequent. My Star Firebirds are used for the majority of my overhead shots, but I'll also throw my Rocs and Wizards as well. I have a 150 class ESP Flick that I just got but it's probably the most overstable disc I've ever thrown. I've only thrown it sidearm so far - I should probably give it a shot on some tommies and see how it does. I haven't tried it myself but I've heard the Latitude 64 XXX is a GREAT overhand disc.