I chose the PPC with Tiger since I do most of my video stuff with a G5 dual 2 ghz.

I believe that the way to target the widest mac audience with a 'first out of the gate' app would be to build a Tiger (OS 10.4) 'Universal Binary'. In most cases, anybody with OS 10.4 (Tiger) could run the app whether they have an older Motorola PPC G4, G5, or newer Intel-chipped machine. And typically, a Leopard (OS 10.5) Intel Mac user could still run a Universal binary built for 10.4.

Please note: my 2 ghz Intel Mac Mini came with Leopard 10.5, but it runs 10.4 Universal binary apps very well and can also handle PPC apps quite reasonably under the built-in 'Rosetta' emulation - but neither my dual G5 tower nor my trusty old powerbook G4 can run Intel-specific OS 10.5 Leopard apps at all !)

If the initial release is targeted for Intel Leopard (OS 10.5 on newer Intel hardware), quite a lot of people with older hardware/OS will be instantly left out of the mix. I believe that an Intel/10.5 specific version could follow later with specific performance optimizations for the lucky ones that have the latest OS on new or very recent Intel-based hardware.