Software Scheduling/Jitter

I have a 2.4 link that I upgraded from an old P7 with software scheduling to a P9 with hardware. After upgrading the link has become very spotty. I downgraded down from V9 to 7.3.6 again an enabled software scheduling. The jitter seems high to me i.e. I see 7-8 at times. I know sub V9 that up to 10 was considered acceptable in 2X mode. How about with software scheduling? Is it supposed to be higher than hardware or still under 5?

Also, what is the difference between a light AP and a normal AP?