Yeah, I registered it shortly after I downloaded the trial. It's a great little manic shmup on the PPC with chaining, grazing and clear Cave influences. It does suffer a bit in the control department, but that's pretty much the case with all PPC shooters, and more a hardware issue than anything. Definitely worth the $10 for the full version.
I think even if there are some Cave influences in Darklaga they're very very superficial.
Darklaga is nothing like a Cave game, it's more similar to Zanac Neo with more random level design and more bullets.