My PCB package is eagle but ive got the cheapo version which is limited to 4 layers,the fpga vendor has got a recommended layout which uses stripboard type layout to control impedance and that uses 12 layers,with buried and blind vias.
So after extensive negotiations with the fpga vendor i have got a bga socket( a ball nest,oh er missus)used for their production testing which usually costs over £400 and after much wrangling got the cost down to something a little more reasonable.As I said to them even if I had been able to get a suitable layout actualy fitting the thing would have been a nightmare.I will contract out the pcb layout for the production version,once the prototype is running
I think that it would be a good little sideline for anyone who can produce a suitable layout to offer pcbs which can convert a bga to a pga or some such device because this is going to become much more common.