The AE 5 controllers can handle quite a few fans per channel. For a good example of just how much they can handle before the fan power amplifiers overheat (about 90 deg. C), and run the fans up to full power, see
this specific page of the review of the AE 5XT From Martin's Liquid Lab .
Martin uses Scythe Ultra Kaze fans, which draw a relatively high amount of power, to load the fan power amplifiers. He winds up having no trouble at all with 3 Ultra Kazes, which is the equivalent power draw of 12.5 Scythe Gentle Typhoon fans per channel. The main limit is how many amps your fans draw per channel. There is some debate over the limit: Martin says 1.6A per channel, I've heard somewhere a max of 5A total across all channels, and I try to keep the load below or near 1A per channel. For what it may be worth to you, with a Laing DDC-1 pump that draws about 1.1A at 12V on fan channel 2, and set to 75% power, or about 9V, the power draw is averaging about 0.9A. The fan power amplifier temperature stays about 64 deg. C, well below the max (about 90 deg. C) at which the AE 5 will try to cool itself off by going to 100% power. I do have the new, taller, aluminum heat sink on the AE 5, but no water block.
On my AE 5 LT, fan channel 1 has an Akasa Apache Black attached to it, and is running it at 9.0V (75% or about 585 rpm) and the power draw is 0.07A, a Lian-Li fan on channel 3, running at about 6V (900 rmp) power draw on the Lian-Li fan is about 0.06A and a pair of Akasa Apache Black fans on the PWM channel, #4, they are fully shut down now, 0 power (which still gives about 550 rpm to these PWM fans), they draw about 0.05A.
Remember that the fan amps heat up only when you have them reducing the voltage to your fans. If they are supplying a full 12V, they barely heat up at all. Further, the lower the voltage that they supply, the hotter they get. So, for example, providing 10V to the fans they run cooler than they would if they were supplying 7V to the fans.
The number of fan channels you use on the AE 5, and on the PA 2, is more influenced by the number of ways that you want to control the fans (example, some fans at 1200 rpm, some more at 800, and some at 500 would take 3 channels), rather than the power draw.
You may find that you are able to load all 11 of your fans (BTW, 9+4=13, not 11) on the AE 5, thus freeing up the PA2 to control other things.