We have 2 types of pavement basically: regular asphalt (ranging from new and smooth to minefield-like, with various degrees of craked pavement in between and all sorts of potholes and other obstacles you'd probably not going to believe unless you see it with your own eyes); and cobble stones (wich used to be sort of smooth and regular, relatively speaking, many years ago; nowadays the craft of cobble placement is going lost, so most of those roads are bad for cycling - unpaved roads like many we have in rural areas can be much nicer actually).

I can't figure why a front loader would behave any worse in rough pavement than a long tail - perhaps you can enlighten me?

Specially considering that any bicycle with an extended wheel base, all things being equal, will allways perform better (confort-wise) in rough pavement. Recumbent riders know that all too well, since even so called short wheel base 'bents have allready a longer wheel base than DF bikes.

I can imagine riding up curbs may be difficult, but I'm not planing to spend a lot of time riding on the side walk anyway.

Could it be that the particular steering geometry parameters of typical box bikes can cause the trouble you're refering to? My next question (after the one about the simple mesurements above) would be about head tube angle, rake, trail, etc. Looks like there are not so many box bike owners on this board, though...

Perhaps you should give it a try, then we can begin to build a shared data base here.

Did you see Tom's tutorial? Very nice even if it's short on details.

http://tomscargobikes.com/BUILD_YOUR_OWN.php