They have a 4 gig RAM option - OK to be soldered in, I understand the need to dispense with bulky connectors to save space as connectors use relatively large amounts of real estate.
The SSD reaches 256 instead of 64.
A Firewire port is added.
The screen is expanded to fill the space of the bezel.
The battery is relatively easy to replace on the go (may already be the case).
Cost is secondary and I feel that I am not asking for too much. At this point I would depart with my MBP 2.4 as it is.
aehaas