[c-nsp] DWDM optics on 6500s

[Jeff Bacon]

I am looking at getting some metro waves (mostly 20-40km) between sites;
I'm working with a provider who is using passive splitters on dark runs
and they're willing to split me out a wave for near the same cost as
just running a gig switched.

Currently, I am thinking of using a 6704 blade with a DFC3B (I'm using
sup7203Bs - no call for the C model in my environ) and buying tuned
optics. 

The goal is primarily serialization latency delay reduction, not
actually running 10G of traffic - I'll be lucky to run 1-2GB (though
it'll mostly be 60-100byte packets). 

1) The cisco optics appear to be in short supply and damn expensive. I
may have to go third-party. I know it's a gamble. Any other issues I
Should think about besides what's been discussed here? 

2) Is XENPAK on 6704 viable? Any gotchas I should know about with
XENPAKs vs X2? 

3) Does 6500 switching performance blow super-hard, or just so-so hard?
(6-15us is ok.) Yes a 4900M might be faster, or a J-product, but I don't
want to change platform really, I need NAT and don't want to use
routers, I want to keep box count down (co-lo), and having a whole box
just for passing 10G doesn't IMO make sense because I'd still have to
get it into the 6500 anyway. 

4) What's reliability on the tuned optics (vs say using a freq-shift box
with a normal 10G optic)? Is this of the level that I should expect
significant BER, or keep a spare on the shelf, or is it pretty much
rock-solid?

As you might guess, this is my first foray into actually implementing
DWDM runs - I've studied it and planned it, but this is now at the "buy
stuff" level, and I don't want to assume I know everything. Relevant
document pointers appreciated. 

Thanks,
-bacon