My two cents as (someone who has been following the game for years but is still) a noob.
I like the thok. I think instead of trying to change Sonic to be more beginner-friendly, it should just be made more clear that he isn't a character for beginners. It is strange that the title character isn't who you should immediately be playing, but that's more of a problem(?) with Sonic as a character himself than with SRB2 - a very fast character is going to be difficult to control. He's not exactly the all-rounder that Mario is.
I know when I first played I thought to myself "well it's Sonic Robo Blast 2, I'm supposed to play as Sonic" even though I was more interested in Knuckles. Later on I started getting my ass handed to me, so I started a Knuckles game, and I had a much easier and more fun time. If I was getting a friend into the game I would probably recommend playing as him first.
If you're dead set on making him a simple beginner character, then I think something as simple as giving him the homing attack would be very appealing to new players who are still getting used to engaging enemies in 3D. I also like the idea of making the spindash more useful for him somehow. I remember very frequently trying to use it to get more distance out of jumps, since I'm so used to Sonic Adventure. But it's pretty useless compared to the thok, and it doesn't feel very good. The physics overhaul sounds very nice too, and I would look forward to it.
