cartridge life is better, but toner can get clogged too
I bought a small laser a few years ago (a Samsung CLP300N) being fed up with printing problems due to clogging ink. The speed and sharpness are indeed excellent, but recently I started to see problems that seemed to indicate the toner was running out.
Turns out it wasn't; but small deposits of toner on crucial parts of the printer's innards blocked the normal 'flow' of the toner onto the drum.
With the help of some guidance from fixyourownprinter.com I managed to clean this up, but it seems that if you don't print often enough these kind of problems will always turn up. Printers, it seems, don't like to stand still for too long.