I have seen that as well.  I think putting an SD card on a HU is a KILLER!!
idea.  I am frankly dumbfounded as to why none of the major HU manufacturers
don't offer this on at least some of their models.  Perhaps someone knows
why.  An CD card slot takes up virtually no space on a HU and those cards
have become incredibly ubiquitous, and quite cheap.  The one I saw at
Wal-Mart was working and seemed to perform just fine.  I actually considered
it while I was shopping for a HU a couple months ago, but I ended up going
with Alpine partly because of their reputation (snob factor) and
reliability.

If you already own some large volume (1-2 gig) SD cards, I think you could
do a heck of a lot worse.  Also, you would have something CLEARLY ahead of
it's time and unquestionably COOL.

MOSFET

Check it out for yourself, how you like it is the only thing that matters. As
for durability its hard to say between any brand, There is always someone
coming in here saying that they are having a problem with a sony or a pioneer
deck and others will say that these brands are the best and they never had a
problem with them. If you fear that the no name stuff will die on you, I'm
sure that it has a warranty and if it dies after that, go out and buy another.
You should be able to buy 2 or 3 of them before you get into a price range of
and Pioneer or Alpine. I bought a no name 2 way lcd car alarm for $80 with two
lcd remotes. Had it about a year now and it still works great, if it dies I'll
buy another one. The way I see it, I can replace the alarm a few time before I
get into the price range of a DEI alarm with those same options.