...
One router knows about 2 paths, the other about 4
paths. Why? Because BGP only advertises the route that
is in use. Everyone here of course knows this, I am just
pointing it out because culling information before
allowing it to be redistributed within your network is
what BGP is already doing anyway. It is possible to
remove some of that information from the local FIB too
without losing anything at all.
Using a default also gives you a dramatically shorter
convergence time if one of the transits goes down.
Having 800k routes can be harmful to your network even
with equipment that can handle it. Yes I am aware that I
am not doing what I am preaching here, but I am
considering it :-).