The Venture 15 was his first multihull design. There were two models, the early one was banana hulls like the Hobie, the second, more like the Prindle. Both were very inefficient to windward, camparatively heavy and slow, I sailed both styles. I also flew out to California in my Cessna 182 and visited Roger MacGregor in Newport Beach, CA and went for a ride on his tall rig 36 that won the Ensenada race one year. That was a very well balanced and fast boat with a 50' rotating mast and a battened main. He experimented with several rigs and settled on a more conventional design for sale to the masses. The stock boat had a 43' mast and conventional sloop sails. He felt the tall rig was going to get a lot of people in trouble. It was harder to right, and easier to capsize.
The first sets of production hulls on the 36 were heavy and had the single very heavy daggerboard in the port hull. The later hulls had lighter weight pivoting boards in each hull and the entire boat was much lighter. That boat had much better speed potential and better VMG to windward due to the 5 degree pivot to the boards than the early version. I have sailed both. I used to be a dealer for them and had a heavy one on loan, and a light one that we sold almost as soon as we got it in. The boards would pivot slightly to windward from the water pressure on them so the hulls would track more in line with the heading because the boards took the angle of attack for lift. The 36' Cat retailed for around $28K with sails, spinnaker gear, and trailer.
MacGregor built inexpensive boats, monohulls from 17-26', some were rather unorthodox designs, a couple of them hybrids - planing power/sail, but all designs that got a lot of people into sailing that would not have been able to afford a top line boat. Many later moved up to quality boats after they were hooked.
Roger was a very smart but shrewd businessman with some very innovative ideas. He was also ridiculed in "yachting circles" for building cheap or strange boats. He closed the 36' cat production to build his 65' ULDB monohull which also won a fair share of distance races. That one retailed for around $120k with sails, initially.
They used to have to restaff the facilities every so often after the INS visits. There were also lots of frequent re-hires. That was back in the mid 70s. They didn't like having their picture taken either.