I still don't know... part of me wants to say:
- Bah, just go through with it. You've got the PCB already, and more than enough money kicking around. At the end of it you'd have a pretty decent amp that (if you make the enclosure correctly) will be fairly portable, and you'll have learnt a fair bit by the experience.
- Whatever, just build a Noisy Cricket for the sake of having an amp. It will be easier, cheaper and you'll have the tools to make it a lot cheaper to come back to this project at a later date. With a decent pair of drivers (which you have) it should sound quite good and will be far more portable.