Another convert. The round nosed cat hull SIBs tend to be much more functional than zapcats/thundercats for the reasons Easyrider had mentioned.
I would imagine that the Ceasar Surfcat would perform similarly to a PVC Gemini Surf GRX 420 (the gemini's are also available in hypalon). The PVC cat hulled SIBs should give somewhat higher performance since they are lighter and can be inflated to higher pressures than hypalon (therefore a little more rigid), but the hypalon cat SIBs perform extremely well just the same.
There really aren't very many roundnosed cat-hulled SIBS on the market. The only ones I'm aware of are;
Ceasar Surfcat (4.1m - PVC only)
AMI Advanced Cat (3.0m, 3.3m, 3.9m & - 4.6m - PVC only)
Gemini Surf (3.8m & 4.2m - PVC or hypalon)
Gemini Dive (4.7m & 5.3m - PVC or hypalon)
The AMI boats tend to be a little less costy than the ones from Ceasar and Gemini, but it is definitely worth your while to inspect them in person to see how they are built and if the extra cost of a higher end brand is worth it. That is not a nock against AMI, they are better built that most SIBs out there, but the South African brands have alot more experience in the design and build of these boats.