I use the 1350 with a PB-2 which has a newly installed Topkit and love it. Whoever makes these Topkit things knows their stuff.

Seriously, HiFlight is the guy to talk to if you are interested in tweaking your amp's sound using different op-amps. He is very knowledgeable about the different op-amps and the nuances of their sound signature. If you describe what you are looking for he can almost certainly provide a topkit to get you there.
He also set me up with some options for my STX sound card which worked out wonderfully. It's not a one size fits all kind of thing. He can tailor a topkit to what you think you want.
As far as the 1350's - they aren't technically full size, but rather 'on ear'. They are incredibly detailed, provide excellent separation, and are good from top to bottom in my opinion. I love them, especially with the PB-2 and especially especially with the new topkit installed. But it depends what you are after as far as sound signature goes. Personally I find the 1350's transparent and crystal clear without being harsh or fatiguing - which is what I want from them. My biggest gripe is the cord which has some microphonic tendencies. There are a couple of threads about them if you are interested.
Some find that full sized and portable don't really go well together, others think the LCD2s are a great portable option. I'm firmly in the former camp.
Have you seen
this review?