Well - most of the paints are a base/clear combination (all of the Subaru
paints, I believe) - so you will be taking care of the clear - as long as
you do that (wash it every now and then, wax a couple of times a year, try
to keep it in the shade when you can, etc.) the paint will last a long, long
time.
As far as pro's and con's - appearance wise, get what looks best to you
(you're the one driving it) - but consider this - modern paint jobs are
thinner than they were in the past, and more prone to chipping (from rocks,
etc.) - a darker color is going to show up the chips than a lighter one -
take the WRX as an example - both blue and black look great, but after a
year or two, all of the rock chips show up as little white specs, unless you
are religious about touching them up (which, unless you are good at it,
looks about as bad) - silver and white, on the other hand, hardly show any
of the marks as they blend in with the lighter color.
I have an '02 platinum silver metallic WRX - there are definitely some rock
chips on the hood, but you can't see them unless you look closely at an
angle.
For mica vs. metallic, I think there is more color depth to the "sparkle"
off of the mica, vs. a whiter sparkle off of metallics. Mica looks very
nice! (on the other hand, they might be the same, and I am just going
insane - but that's the color difference I have noticed)