Well those new PS3s would probably have a higher firmware than 3.70 or thay will probably be blocked from downgrade...
Otherwise I think I would go and get myself a Red one... Hmm wonder if you can flash a Jp PS3 with an US firmware to get it to become as an american PS3... I think the JP PS3s has X function button as the O button... weird that they don't have it in the same place on all PS3s I think...wonder what the reason can be tho... (can always use rogero's key changer)