Mark, the Solent ribs 6m is a very similar hull, although they may not thank me for saying so. Just bought a 6.6m Tohatsu hull but haven't tried her on the water yet. Tohatsu seem to market them in busts and then go quiet for a while. Mine is 4 years old and there is not a mark on her and seems well built.
Spent a weekend in March on a Solent 6.5m and was very impressed. The biggest let down was no elephants trunk had been fitted (at the request of the owner) so water had to be pumped out, a major draw back in my opinion. Also the throttle had been mounted vetically so finding reverse ment pushing the lever a long way down and didn't lead to a good set up to practise boat handling with. However both are minor faults.
Tubes don't touch the water at rest or lightly loaded which is one of the reasons they manage good peformance figures but the down side is any rib like this isn't as stable and wouldn't suit divers getting kitted up but shouldn't matter to a user looking for performance or a run around rib.
Porters make the hulls and they also have a web site which you might want to look at or visit them in Emsworth.
As John says the 90 Tohatsu isn't the latest technology but its tried and tested which could be reasuring on the water.
hope this helps