My seios occasionally seize up too, however I've figured out a reason for this, it means there's too much build up on the ceramic shaft, it literally fuses with the impeller, a soaking in vinegar tends to cure this (of course you need to get the shaft out... whack it.. but carefully
). Then the pumps run fine, however still have not figured out why they will occasionally fail to start up after a power outage. or I unplug them.
Koralis are nice, however they are pretty damn large for what they put out, the biggest one is only 1200gph or so IIRC. If you add size to a tank, make it a push a lot of water.
Tunze are nice if you have the money, right now I'm not willing to dump that type of cash on a pump, not to mention the controller too *ugh*.
Other options are closed loops too, maybe with an oscillating device (Ocean's Motion?) they can run a few bucks too, but not Tunze bucks.