Is there an advantage to using a bulk subber in this scenario?

[ChasingZion]

I have enough cards (100+) to meet discounted rate for both modern and ultra modern. Should I just send the cards directly to PSA or do group subs get picked first? Turnaround time improving would be an enticement but I'm not sure that any of the big sub guys receive that treatment but if so it would be nice.

I could use the 15 free vouchers if I do it myself. I also have approx. 600 cards to be submitted if that affects the decision at all.

Any tips/advice is much appreciated. Thanks!