If L. Ontario will be where you do most of your boating, the only type of SIB that I would even consider would be a Cat-hulled SIB. That leaves you with a choice of 3 brands, which are;
1. AMI 'advanced cat' (3.3 - 4.6 meters, PVC only). This is a Seattle area based company that has there boats manufactured in Taiwan. There is a dealer based in Sidney, BC. who goes by Mad Dog Extreme.
I took a small one of these out for a test drive. It was OK but not built anywhere near as beefy as the Gemini (and I would imagine the Ceasar) boats are. You'll notice that the very bottom picture on their homepage is actually of a Gemini zapcat rather than one of their own boats (what's up with that?).
2. Ceasar 'surfcat' (4.1 meters, PVC only).
Ceasar is a South African based manufacturer that also builds RIBs and are probably best known for their thundercat racing boats. While I personally have not seen a ceasar surfcat, they have an excellent reputation and strong following. Easyrider, who is a member of this forum, has a surfcat and is extremely impressed with it. There is a dealer based in Florida.
3. Gemini - which is another South African based manufacturer with an excellent reputation.
Their series of cat hulled SIBs include the Surf GRX (4.0 meters & 4.2 meters - PVC or Hypalon),
and the Dive (4.7 meters & 5.3 meters - PVC or Hypalon).
If you were wanting a boat that you could keep on a trailer through the summer, then fold up for the winter, I would recommend the Dive 530 for Lake Ontario use. However, neither of the Dive models would be practical for setup and take down with each use, since they are much to big. When folded up, my Dive 470, outboard and gas tanks completely
fills up the (long) box of my Dodge Dakota.
Realistically, the Surf GRX 420 would probably be your most practical choice of the Gemini models for set up and take down with each use. You would still need either a; small car with a small utility trailer, a quite large car with folding back seats, or preferably a pickup truck to haul a 4.2 m Surf GRX along with motor and fuel tanks.
The other thing to consider is whether you want a PVC or Hypalon boat. A PVC boat is lighter and can be inflated to higher pressures, thus giving higher performance. A hypalon boat will have at least double (probably closer to triple) the life expectancy of a PVC boat. Hypalon will also cost a little more.
There are only 2 North American Gemini dealers, both are in British Columbia. I would highly recommend either one. They are Orca Inflatables in Vancouver, and Hi-Tech inflatables on Vancouver Island. Here are their websites: