If you have the tower space use two PTP's. You'll get better speeds and more resilience to noise.
I have the space but as the links are limited by the DSL's speed anyway (6.5MBps down and 750kBps up) how relevant is wireless speed?
In what way "more resilience to noise"?
Here's a good remark! I see lots of guys trying to squeeze high to very high data speeds over their networks while I also see a lot of guys trying to distribute less then 1Mb Internet access to their clients on their network.
Either there are two different group of users mixed up in this forum which is not even been taken in account by these users themselves or lots of us get blinded by the need for high performance while then they have no use for it!
I think most users on this forum are internet access providing only and can do with low to moderate network speeds. Only the real big players with hundreds or thousand of users, with fibre lines or better and with corporate networks were traffic exists between users within the network need the highest network speeds possible.
I have two 8Mb ADSL line to distribute amongst some 100 users for internet access. I sell 3Mb download to them. In theory I will then have a maximum of 2 x 7,5Mb (that's what I really get) = 15Mb tcp data flow on my network.
So with some extra overheads and reserve I should be fine if all my links (ptp or ptmp) are 24Mbps minimal. My network is actually 36Mb everywhere and the backhauls are even 48Mb in most cases.
With ¨resilience to noise¨ I think JJCinAZ means that with two separate radio channels for each ptp link you would have less problems with noise.
I don't know, I don't think it would make any difference for the AP radio if he has to deal with one station or two.
The other (station)radio's also have to deal with noise. It is the worst one that sets the standard.
In case one station has the worst s/n ratio that link might suffer from that. It will not affect the other link, even if both links are handled by one AP radio.