if its over 7kg, you need PCM anyway, dont think yours will be tho. But its safer to do that, as said above. I use nothin but PCM from my funtana, to my 44% Cap 232.
'need' is kind of strong wording. there is no legal requirement for any particular size, you could even use AM or 27 mhz if you really wanted to. lots of people use standard ppm rx's with large planes, and there are advantages to ppm also. (you actually see glitching, whereas a pcm is all or nothing)
5-6 seconds? which rx's take that long? my futaba 8 channel pcm takes a little over a second to to to FS.