I am also currently building this kit, with a LOT of additional
scratchbuilt detail. It's been sitting unfinished on a shelf in my
modelling workshop for the last 4 months, but a few days ago I decided
to try and concentrate on finishing it. Currently I'm working on the 5"
director radar, the funnel searchlight platforms and ladders, and the
bridge/forward superstructure details. Hopefully I'll post some more
photos soon (I posted some "work in progress" shots a few months ago -
search for "Fletcher" and you'll probably find the thread)
I'm intending to scratchbuild the AA guns and other small fittings, and
cast copies myself in white metal, as HR Products aren't available in
the UK and ordering them from the US is a pain (they don't accept
credit card payment). I definitely recommend using HR Products parts if
you can get them however.
One small tip for this kit. If you assemble the 5" turrets according to
the instructions, the gun barrels are noticeably too short. A fix for
this is to cut the "breech" off the barrels, glue a short length of
styrene rod of the same diameter onto the breech end of the barrel, and
then fit the barrel into the turret blast bag from the outside, using
the styrene rod as a "locating pin". This adds about 1cm to the length
of the barrel.
It is certainly a huge amount of work to get this kit to a decent level
of detail and accuracy, but (if you can put up with the inaccurate hull
profile) it's (probably) easier and quicker than scratchbuilding.
Good luck, anyway! I'd be interested to see your work once you've started the build.