IMHO, you have to have 'best blend' of direct peering at peering points as
also having dual homing to upstream - ofcourse depending on size.
1.it help keeping resiliency and
2.provide optimal route to your customer - No matter how much fine-tuning
you do in attempt to provide optimal path to your customer, in absence of
direct peering, some of your customer have to bounce back accross
atlantic to reach to network within their own country - not a good
'economics' for your customer and so to you. Also where there is metered
base charging by your upstream provider, you end-up paying less to the
extent traffic is carried by your peers and vic-e-versa or
3. go for private peerign connection. No congestion :O)
The cost of peering has to be viewed from the perspective of complementary
to each other and resiliency point of view rather than in absolute
'economics' term.
As for congestion, you can't miss it- no matter which alone option you opt
;O)
Best Regards
Hitesh Patel