I think I would take an RTP with a slot over an MCX with a 1:1. I have too much good experience with the bulletproof Vortec TBI precursor to the RTP to count it out.
The problem is that the 197 had such an increase in wetted surface (post hook) than the previous hull, that it needed more power to push it around in the same manner to which many of us had become accustomed. But given the "stated hp" notes in the other thread, I'm not sure how much you're giving up between the two engines. Plus, right around the 2005 time frame, the MCX got the ETX CATS, but the RTP did not get them until the next year. That would play into my buying decision (I don't care that Indmar "said" that there was no reduction in hp with the cats).
With the 1.52:1 gear reduction of that era, I'm not convinced there would be too noticeable a difference for slalom between those two engines.
Previous: 1993 Prostar 205
Red 1998 Ski Nautique, PCM GT40, 310 hp, , Acme 4 blade, Perfect Pass SG/Zbox.
Be kind. Have fun.