I have a 1258(actually, the Spektrum twin H6040) on gas in my DM-1 and it's flawless. Very fast too. Will be my next gas/brake servo in buggy, as my old Airtronics servo is getting rough. Savox 1258 for gas/brakes is an excellent value for money, 1256 if you want a lot more torque but less speed.

I happen to believe that a 1/8 buggy doesn't need 20 kilos of torque for steering, but like really quick response, so for me I'd run a 1258 on steering too. I have the cheaper Tower/Hobbico Hitec 5955 twin on steering in my DM-1, and a Hitec 5955 in buggy though, which are great because they last forever.