It's my understanding that laser printers generally shouldn't be on a UPS for the reasons you cite - namely they have power spikes where they draw a lot of current. If you don't absolutely need to have it there, you might want to consider just having it on the "surge" outlets.
My recollection of this rule of thumb is probably from the LaserJet II days, so it might be obsolete, but I don't have our Lexmark E234 on our office UPS for that reason. And it seems to still be a common recommendation - http://articles.tech...8_11-6085460.html
Good luck!
Cheers,
Scott.