Look, I can do a "show interface" on any interface and see what speed it's running at and if it's dropping packets. If BGP hears a route on an interface that isn't dropping packets shouldn't _that_ route be considered "best" all other things being equal (hop counts and all)? You can't tell me the router doesn't know this information because _I_ get the information from the router itself!!
I understand about route instabilities, etc. All I'm talking about here is a better "tie breaker" than ordinate numbers of IP addresses.
The router really can't see how fast an interface *can* go unless it's maxed out. That's not really useful information in a route-selection decision. It's possible that the packet loss might weight a better path but you would have to be careful about reweighting 20k paths every few minutes... Especially if you pass those decisions on to other routers :) Avi