no.
*headdesk*
there's no such thing as 'too much at that size' (until your eyes become inadequate to actually resolve the theoretically-possible detail, which is a point much higher than 1920x1200 at 15"). Higher resolution at the same screen size simply improves sharpness. It doesn't 'make everything smaller', unless your OS is crap; you just set the DPI setting correctly and you get everything the size it ought to be, but sharper than if the resolution were lower...
OS X is supposed to be reasonably resolution-independent, from all I've read.