Wireless Access

There are several thoughts on this and it all is site specific really.  Can you share more about what this upgrade entails and use cases/business requirements?

Basically, you CAN mix and match although the channel widths should be set to 40 MHz vs a mix of 80 and 40.  This is to avoid any client confusion and channel overlaps in the overall RF network.  We recommend that an entire wing/floor be swapped out if budgets don't allow for a complete building upgrade.  However, a salt and pepper can work if configured appropriately although used as a last resort.

If you are doing a 1 for 1 replacement, is the current deployment based on coverage or density?  What is the signal quality today and will new applications like voice and video be supported by the new deployemnt?  This will dictate if more APs may be needed.  In some cases, we are doing a 1 for 1 and in others, we are adding to support more density or improving the signal quality.

The ARM behavior should be fine and not need to be tweaked epecially with ClientMatch on 6.3.  

See here for more depth -  http://www.arubanetworks.com/pdf/technology/MG_80211ac.pdf

I had done it with both hospitality and enterprise spaces doing 1 to 1 swap with AP105/AP93 with AP225 and we just let the ARM run. There is no complain so far but with client match enabled it is not working 100% (Around 80%) like what we wanted but overall performance is much better compared to AP105 and AP93.

I always try to discourage "slat and pepper" approaches. In my experience, they usually end badly.

Client devices tend to make REALLY poor judgements in terms of which AP to connect to when the RF "playing field" isn't level.

I would support Seth's comments, you could adjust configurations to make all AP RF capabilities similar and avoid client challenges. But on the understanding you'd have to do this by reducing capabilities, there's an argument to say you're wasting asset resources/investment to a point.

I try to keep RF capabilities in a single contiguous geographic space consistent. Results are generally better that way.

Thanks for the feedback guys. This is a small floor just a few aps (5 - 8). They are stacked .. 

In your environment it should be alright.My what the rest mention is correct, if it is a big setup normally redesign will be key for good throughput. I had swaped out AP105 mainly for dense areas such as auditorium, lecture threates, canteen etc.