1500mm/s^2 = 1.5m/s^2
1.5/9.81 = 0.15 G
Joel, I haven't seen drawings for your design modifications? Or are you proceeding with your initial design? I think machine flex might be your limiting factor in determining acceleration. I don't think you'll be running this at 0.15G, but many people are happy with less, and many people also select parameters far less than what their machine is capable of to get within their comfort zone.
As far as 0.15G being huge in general, not specifically related to Joel, here is some info I have found on the zone:
Jim Dawson is running at around 0.12G on his big moving table CNC using a single Nema 34 1280 ozin at 400 IPM cutting speed with a table of approximately 700 lbs.
Ger21 mentioned his goal is 0.5G for his build. Is that right Ger? Of course he's using 400W servos.
The last build that 1Jumper10 did for a friend, he mentioned it was running happily on 0.13G (50 in/sec^2) but that he detuned it to 30 In/sec^2 (0.077 G) to where it's less anxious to learn on.
linux_fan said "Acceleration is 1500mm/s*s Can go almost as high as you want with those mitsu servo motors, but it hurts even watching gantry at some high acc rates" in his post about his awesome machine here:
http://www.cnczone.com/forums/uncate...aluminium.html
This is linux_fan's video, so this is what 1500 mm/s^2 looks like