Smaller is harder but I'm not sure it matters. One of those magnifying circular light dealies is recommended. Parts count is the killer. I just finished the prelim parts list and pushed it to github. There's 320 parts on that 10x10cm board. Ouch!
(Someone please send me a Pick n Place machine)
70% of those parts are decoupling caps for the ASICs. Is it really necessary to have 14 per ASIC? As a back-of-the-envelope calculation, I get about 5 nC of charge per clock cycle (based on 1.5 A @ 282 MHz). With 0.8 uF of lumped capacitance, neglecting ESR/ESL, that's about a 7 mV drop, which is small. Maybe you can get away with less? Maybe you can use larger capacitance values but fewer caps overall?
I suppose the only way to know is to do some in-circuit testing on actual ASICs.