I once bought a DP boat when I was younger and thought I knew all I needed to know about boats. Ended up with a complete new bottom!
Whilst rare, there are a few DP boats about that were used as hireboats (particularly on the Llangollen) - mine was one of them. The result of each 'corner' being dragged onto the shallow bottom during mooring up and setting off had worn it away - apparently it's a common problem with ex hireboats in the area. But mine was much older thatn that.
They always used to have wooden handrails (and doors) on their trad boats I believe - mine certainly did.
I think someone was quite correct, they had a sort of cult status - but the reality was that there were other better boats around.