I have the Eheim 1048 in my system now, it pumps water through 5 water blocks (CPU, HD, NB, VGA, and some power module for my Gigabyte mobo). The radiator is a heater core out of a '78 El Dorado.
It does the job, the CPU temps hover at about 8-10*F above room temp. The only problem I have is when I first start it up after I have completely drained and refiled it. It takes hours for all of the bubble to finally bumble out of the system.
So, should I spend the $59 and upgrade to a 1250? Or just live with it?
If you are getting temps like that then there isn't much of a reason to upgrade. The only dramatic difference will be the filling/draining time for the system. There is a delecate balance between cooling efficiency and flow rate. It seems you may have found your balance so a little headache once in a while isn't worth loosing those good temps. Higher flow can reduce the cooling efficiency of the system.
dude, why would you upgrade ? the bubbles you're getting are because you're actually turning the thing off and on again.. the 1250 would do the same thing... just don't turn it off, its your best bet (besides, why would you turn a computer off )