The carmel flavor should persist. I'm not sure if you are talking about
using carmel candies, but if you do, I would make sure they are all
natural. The regular ones you get from the store contain artifical
colors, tickeners and possibly other stuff that you probably wouldn't
want in your beer. Even if you find natural ones, I would limit the
amount to prevent cidery flavors.

I did a batch a while back where I took out about 1.5 gallons of wort
and boiled it down to about a quart (stiring often and reducing the
heat as it got thicker). It boosted the carmel flavor quite a bit. You
can re-add in the lost water later if you want, or if you are going for
a higher starting gravity, just leave it as is and re-incorporate it
into the full boil. The advantage to carmelizing the wort as opposed to
adding carmelized sugar is that the sugars in the wort will not add any
off flavors.