With each tank feeding two markers you'll need to have quality regs on those tanks with a quick recharge rate or else you'll suffur horrible shootdown when shooting 20bps with each marker. Hell, just shooting over 10bps may cause shoot down. I noticed you had a couple PMI tanks and they'll start having trouble supporting a marker shooting above 30bps due to their 30ms recharge rate. I'm not sure what the recharge rate is on the other two tanks, but I figured I'd just mention that little bit of info just incase you over looked it.
Other than that, it looks great and I'm sure you'll get a lot of newbs running in fear.