How is it possible that the new R710 AP archieves 800Mbps with four streams. Compareable products only archieve 600Mbps. Is this a typo or did Ruckus find a way to enlarge the bandwidth? If so how can normal clients be compatible?
Ruckus does two things in 2.4GHz. Obviously, there's an extra spatial stream which takes you up to 600mbit. But the new thing is 256QAM -- the 802.11ac 5GHz modulation scheme has been made available in 2.4GHz now.
This technology is marketed as "TurboQAM" in Broadcom, and has been on consumer chipsets for a long time. Anecdotally, I have noticed that at least in relatively RF-clean consumer environments, this really does work, leading to much faster apparent speeds on 2.4GHz.
Now, the interesting part is whether or not Ruckus is still using QCA chipsets in the R710, since traditionally 256QAM 2.4GHz has been Broadcom exclusive.
As far as client compatibility, I don't have a full list, but I believe most 802.11ac Broadcom chipsets support it. And Broadcom is the most popular wifi chipset vendor by a large margin.
I would say that it's a very wise and logical solution -- there are 3 probably potentially most practical improvements in 802.11ac -- frame agregation, 256QAM and MU-MIMO. They can provide maximal real impact on data throughput, and all 3 can be used in 2.4 GHz (and at least 2 of them are easy to implement), so it makes sense to use them. Especially as anyway all new chipsets will be probably based on 802.11ac chips, just scaled back to 2.4GHz. The most loud feature of 802.11ac -- 160 and 80 Mhz channels, of cause can't be used in 2.4 GHz band, required completely new hardware and is practically more or less useless even in 5GHz band (but as this numbers and associated theoretical rates are heavily used by marketing, this feature probably justified it implementation enough this way).