If he's your primary, then i wouldn't waste much $$ on a better trainer or anything. Just let him get random pops, and he'll be good as a starter in D.V and a backup in D.IV. After that, he really wont have the ability to keep up and/or you'll run out of time to make him hit his cap.
There are quite a few guys that are easy to dumpster dive off of the TL even at this point in the season that can do more for you long term and have Perennial or better to start with.