Hi Jonathan, 1:1 is a heck of a lot harder to put back on the rails when you fail to set the turnout correctly!
I think the detail on the Proto:48 stuff is driven by the much smaller market - with no mass-produced, injection-moulded trucks it is hand-assembled from brass castings, which lends itself to including more detail. I gave P48 serious consideration, only decided against it because I have too much invested in Ow5 already, plus I have a few 1:34 scale models of NZ equipment that I like to run occasionally, for which 1.25" IS near-as-dammit correct.
I have produced P48 and Ow5 versions of a brass truck for a US retailer, and the P48 version was so simple to make, just copy the drawings exactly, whereas the Ow5 version was a pain in the butt, worrying about clearances, having to decide what detail to sacrifice in order to fit the over-width wheels etc.
Regards
Paul Woods
NYCSHS #7172