Reading through burnin's and others designs it looks like these chips probably exceed 2A each if you overclock more than a little bit.  Have you had any results running say, 8 chips on a 16A regulator (or 16 on 2x 16A regulators) and overclocking/overvolting?

Your buck is at 600khz while avalon's is at 300kHz, both spec'd at 2A/chip, so you should have somewhat better OCability, unless the current is the first limit you hit.