Load balancing is a funny stuff. Its utility is very limited by the fact that you've got to keep packets in sequence to avoid triggering TCP fast retransmits.
I.e. with ciscos you can only do load-balancing on paths (i.e. load one circuit with traffic to ISP A and another to ISP B etc) or on destination networks (that has a potential of causing very skewed load distribution).
I admit I'm not familiar with the impact of 'ip route-caching' tens of thousands of equal-cost paths at dual-HSSI speed. I was told by some at Cisco that it wouldn't be a problem.
Before i left Sprint i produced a plan for them to increase capacity at least four-fold using combination of load balancing and hot-potato intra-backbone routing. Going to OC-3s is a lot simplier, though :)
True, it's simpler - but one does what one needs to do to stay alive. Or one should, at least :)
--vadim
Avi