Nope. Any pre-sale packs that I buy will all be at the end, in one lump purchase, to get the bonus packs. My original plan was to get ~500 pre-sale packs...
But so far I've been selling all my vouchers (because they're worth about $2-3 at most, so I'm happy to dump them for $20)
For vouchers to actually work out, the promo card would have to be over $1000 each (more than double Yodin Zaku or the Llama) and that seems pretty much guaranteed to not be the case, especially since every copy will hit the market at the same time.
If/when vouchers drop back down below $7, I'll buy a bunch up.
If they stay over $16 each, then I will sell all of mine, getting close to $8k in the month airdrop, and I'll spend (at most) $2500 of that getting a level 3 Doctor Blight.