Hi Richard,
The Humber is the same beam and 6.3 long compared to the 645 /655 Ribtec.
Dont know about the weight of the Ribtec but the Humber is 470Kg (bare boat + tubes). I suspect your right the Humber is almost certainly lighter.
I like the idea of the 'Pain Barrier' thing!
Just hope I don't become another MOB too soon - could hurt!
Still, I will nearly always be out with other boats - safety in numbers!
Regards
Nick