John:
I would assume that Javier's environment includes areas of indoor coverage w/ "light" construction that's not very challenging to WiFi propogation, that his APs have good overlapping coverage, that there's no interference from competing WiFi or other devices, that his channel plan is "stable" (with APs not changing channels often) and that his iPhones (when in those areas) still "disconnect constantly".
Hopefully Javier can confirm all those things.
Do you think it's possible for Javier to adequately describe his environment's "unknown factors"?
or.. that his issue goes beyond what can be addressed in a forum like this?
I'm noticing that Javier is using beam-forming R500s and non-beam forming R300s.
(and having problems when physically roaming from R500s to R300s)
Personally, I would use the R500s and R300s in different areas, as opposed to using them close together in "unobstructed" areas.
If Javier puts all his R500s in one area and R300s in another:
It would be interesting to know if Javier still sees his iPhone problems in areas w/ R300s or only in areas w/ R500s.