Vendor Differences in PoE Allocation

Hoping to get some external input on a PoE topic that's been bouncing around my team lately.

In Aruba's world we're getting feedback that the ProCurve switches will provide the exact power needed based on the connected PD + any accessories (eg USB or PD pass through). So if an AP needs 10.3W, it gets exactly that from the switch. I tested this on an older 5406 and the switch does seem to be calculating PoE utilization in this manner.

Conversely, on the Ruckus side of things we're being told that the ICX switches will allocate the full power for whichever PoE-class the PD reports to the switch. So if an AP reports itself as Class 3, the switch apparently reserves a full 15.4W to that port even if the AP is only drawing ~12W. Another source has also told us this behavior is configurable to behave like Aruba, but I have not been able to verify and I don't have an ICX switch on hand to test it myself.

The AP datasheets are adding their own confusion to the mix:

• Aruba AP-303H DS says 9.7W for max idle, + 6.1W for USB + 15.6W for PD pass through = 31.4W worst-case (??)

• Ruckus H510 DS (<PDF) says 9.2W for max idle or 12.95W total max with PD pass through - no mention of the USB draw at all

This can make a huge difference in total switch counts at bigger sites depending on how you do the math, and also makes cross-vendor comparison builds really difficult. What have you all heard and/or experienced in the field when calculating PoE requirements?