Whilst it makes sense to evolve from 802.11n (a 2009 standard) to 802.11ac, I think its impact at present will be rather limited.
The most important thing to note is that 802.11ac does nothing for 2.4GHz operation - realistically, 802.11n squeezes as much as possible out of that band.
Gradually 5GHz support is becoming the norm, which is a good thing, not least as the band is much wider and less congested than 2.4GHz. I have no problem using 40MHz channel width on 5GHz with my 802.11n gear. The big drawback - and also in some ways, the advantage - of 5GHz is that is usually attenuated much more quickly by distance and building structure than 2.4GHz.
At the moment, 802.11ac is a draft standard, so all devices are being produced to a best guess of the final standard. The only mandatory feature is 80MHz support, which takes the maximum speed per stream from 150Mbit/s (40MHz 802.11n) to 325Mbit/s, or 433.3Mbit/s if the 802.11ac gear supports the optional 256QAM encoding.
Whilst draft 802.11ac allows for other features that will take the speeds and the overall performance far beyond what is achievable on 5GHz 802.11n, the reality is that most consumer 802.11ac gear in the marketplace currently is likely to offer double your 5GHz 802.11n performance at best. It's worth having if available, but I wouldn't be rushing out to replace existing wireless gear.
I find 802.11n on 5GHz performs very well, and have no need of 802.11ac at the moment - but I use Wi-Fi equipment more typically found in enterprise settings (HP MSM460 dual band 3x3 MIMO access points, laptops with Intel 3x3 MIMO cards if possible - this combination can manage up to 450Mbit/s on 5GHz).
Edited by David_W (Fri 25-Oct-13 16:01:12)