Yeh, they do seem really cool, and you're right about the labour of love bit - but that's just boats innit. But when ya can get good a reasonable P21 with motah & trailer for similar, seems difficult to justify.
They are great fun, I raced one in Guernsey years ago, but the novelty soon wore off, 6K for an 18 year old toy seams somewhat on the high side - and they dont half fall over quick!