My Slash is set up with a Castle 4600 as well, though mine is completely stock other than a 2.4. I only race occasionally, and even then, I'm slow regardless of what I drive.

If your Slash is dialed and you've got experience with it, I'd say stick with it. I'm jealous of all your RPM parts, though I haven't had any issues with the stock parts yet (haven't had it that long).

The SC10 is a great truck, but it's not going to be all that different from the Slash. It's still a 2wd SC truck. Better handling, but more fragile in comparison to the Slash from guys that own both.

I'd keep the 2wd Slash and get either a 4x4 SC (Hyper 10SC or Slash), or a 2wd buggy. Just to try something different.

If you really like SC and want to stick with it, I had a conversation with a guy a few weeks ago that owns the Slash, SC10, and the Blitz.

He considers the Blitz to drive better than the SC10 and more durable than the Slash.

The Hyper10SC is the priciest SC option, but it look REALLY good as far as quality and design.