[j-nsp] Why should I *not* buy an MX?

[nachocheeze at gmail.com]

We've been using Juniper M/T series in service provider scenarios for
a couple of years now, and really like them.  As part of an equipment
life cycle refresh, we're considering replacing our core (campus
enterprise) network with something in the MX series; a la this post:

http://marc.info/?l=juniper-nsp&m=122008030004203&w=1

We are very "glass is half empty" on our evals; while it seems most
are pretty happy with the MX boxen, I'm trying to find something
show-stopper that would make us go with another product.  We're
wanting basically a campus Ethernet version of an M/T box and all that
that implies (besides just shoveling packets at a non-blocking line
rate, we'd like full MPLS and RSVP/TE support, L2/L3 VPN, multicast,
IPv6, lawful intercept, etc), so I'm curious if anyone's demo'ed an MX
box as a campus core router and tested everything but the kitchen sink
and found something that Juniper says "works great", but in actual
practice just isn't quite there yet.

Basically, can someone give me reasons apart from "we don't need SONET
or any other WAN interfaces, and it's cheaper per port", why should we
NOT choose an MX box?  Are there any gotchas waiting in the wings for
someone who's used to the full flavored goodness that is the M/T
series?