Hi David, You have better taste in boats than I do! Puffin is beautiful. Kind of a poor man's Trinka. They are fiberglass rather than plastic which would explain the price difference.
I think the Plastimo would probably be competing with the Walker Bay rather than a pretty boat like Puffin.
I'm thinking that the 8' Plastimo (PRS245) may be less tippy than the 8' Walker Bay.
If I did the math right, the Plastimo has a beam of 58 inches and hard chines.
The Walker Bay has a beam of 50 inches and soft chines. I think that's why they made inflatable tubes to strap on the sides.
The PRS245 has a load capacity of 250 kg vs. the 8' Walker at 170 kg.