i dunno if there are any class 6's out there that are crap (afaik the class rating isnt based on random access speed which is what's really important for nds games) but you can also get a-data 8gb class 6 for $15.49 if you're lucky enough to live in the states and therefore able to use bloody newegg (
here), and my 4gb a-data class 6 has been great so far. so yeah transcend, a-data, all good. i think.
im sure the kingston are fine as well, just dont treat them like theyre untouchable. theyre not and never have been, its just that in the pre-hc days their rebranded toshiba cards were the best. but about a million other companies rebrand toshiba cards as well (integral, dane-elec, bytestor come to mind) and the taiwanese manufacturers have more than caught up - i dont think toshiba are even making class 6 microsdhc yet.