SP MK17 S555 vs. Apeks XTX200

[lautmaschine]

Yes, my understanding too is that the S555 has essentially the same performance as the S600 -- just lacks the adjustment knob, making it mechanically simpler.

I've owned a G250B since 1993, which I believe is the S555's predecessor. It works as well as any reg I've tried, if not better. Scubapro's parts for life deal isn't bad too...