The Peak and 570SS are not on the same level. Peak would compare better to the 460SS. The Apex competes with the 570SS and they use most of the same parts except the Apex has a larger blower. Same engine.
Between those two I'd probably still take the Peak because I prefer Prochem. Also, if it's a new Peak GTX2 then it will have newer style extra exhaust heat exchanger, but no helix-coil liquid to liquid heat exchanger found on the Apex and 570SS.
Note also that they are owned by the same company and it is possible Prochem machines may be phased out in the not too distant future. There's been talk of an "Apex 570" that is just a 570SS. Stupid idea, in my opinion.
