The SRX seems to me to be more a firewall than a router. I've got Netscreen's handling access to services (reasonably proficient at ScreenOS). I don't need firewall/IDP at the border just routing and policing/shaping
The J2320 is slower and about 2.5 times the price of the SRX220H (looking at RRP at a local distributor).
The J2320 holds more BGP routes - but only 400k which is less than the global table right now so it's kind of a moot point. J2320 can also do 32 BGP peers while the SRX can only do 16. Other than that, for a small scale router the SRX is great.
I run BGP signaled VPLS and L3VPNs with RSVP and IS-IS on the SRX just fine - there are no routing features sacrificed in favour of firewall features. It all runs JunOS.
--
Cool I shall take a closer looksee :) Cheers JT