I'd do both, we put a lot of money into DR infrastructure, and I think with this strategy in mind.
Traditionally, LA kids didn't get a lot of help until they were stateside.
By putting in resources into coaching mechanics and strength training, etc. after three years they become more like college juniors at 20 (a couple years ahead of college pitchers who don't get the same training at 17-18), and you bring over the pick of the litter and start them at Clearwater or even JS. This way they don't count against your domestic roster limits unless they're bon fide prospects.
The better competition in the DR going forward will also make evaluation of their progress easier, since it should approach or exceed the FCL as teams keep players in the DR for an extra year or so. You should also scout the DR leagues more intensively, looking for players other teams may undervalue as "throw ins" when trading.
And by committing resources to player development in the DR, you can take chances on position players with strong arms who lack hit tools b/c you can devote a season to just teaching them how to pitch.