I don't know the newer M,N,P Lycosaurus and their 160hp conversion.
I was referring to the older Continentals O300 compared to the SP. I just digged out the real numbers - usually fly my F172H 145hp Continental at 2.450 rpm (climb prop) with 6.8GPH Mogas at about 95-98KTS. I also frequently fly our C172SP 180HP Lyco at 2.200 rpm (cruise prop) with 8GPH Avgas and at about 108-110KTS. Both settings give about 65% power according to POH. Never saw 115 with 8GPH on the SP's our club have, that would be more like 9-9.5GPH for 115 - one is 2003, the other 2009 (heavy, due to G1000).
So my personal experience is, that spending 200k EUR more give me a 10KTS advantage, but 94kg less load (the 6-cyl is the far better lever for W&B) and about 5 EUR higher fuel costs per hour (roughly 1.2GPH less with 1 EUR/L cheaper Mogas) - ok, I admit also a much louder plane, but isn't the old roaring 6-cyl sexier compared to the rattling 4 ... ?