From what I experienced since we are talking about ESCs lol, the Speed Passion Silver Arrow V2 was smoother than the RX8 I had. Power was similar, but the SAV2 is a big girl.
The Viper ESC I am interested in, just wish tower carried this brand. I also like the fact that in comparison to other companies, they feel there ESC is worth standing behind with a 1 year warranty like Castle does. I wish SP would do that, but, since their SAV2 is like $70 new with 90 days warranty, was willing to go with it. $200, then I would have to think hard lol.