You are far better sticking with one ship for a while, and swapping rarely unless you're seriously loaded.
And, having flown both, I'd strongly recommend the python class cruiser over the regular python. The hold is bigger, and it's faster, plus the extra cost for that sharky paint job is well worth it
However, the python will let you build up some decent cash reserves pretty quickly if you stick to milk runs. Galaxy 2 has a nice set of planets clustered around the tech 15 Texaeded, which is handily close to where you will go anyway after picking up a certain mission in galaxy one.
My advice, is stick with the cobra until you're done with the missions you pick up in galaxy one, then spend a while in a python doing milk runs near texaeded, and buy a PCC to go hunting with (or, if you do well, go straight to the PCC, it's equally capable of milk runs).
