I would personally like to see smaller channel spacing to avoid noise and increase coverage area. Is there any possibility of this being added. I know that this would decrease throughput but if you only need 512k then it would be fine. Thanks
1.25mhz
2.5mhz
5mhz
10mhz
20mhz
why not 0.25 and 0.01mhz ? 
I think there are technical limitations behind this
There probably is somewhere but avalan wireless has 900mhz and 5.8ghz equipment that uses a small channel. Here are the specs for the 900 gear. If these smaller channels were available then we could overcome noisy areas easier. Thanks
wireless 1.536 Mb/s
ethernet 935 Kb/s
+21 dBm (4 Watts EIRP used with 15 dBi antennae)
-97 dBm at 10e-4 BER (-112 dBm with 15 dBi antennae)
148 dB with 15 dBi antennae
40 miles LOS with 15 dBi antennae
12 non-overlapping with 2.0833 MHz spacing and 1.75 MHz occupied bandwidth
Channel selected with DIP switch or via Web browser interface
RF RPTNC Female / 10-100 baseT Ethernet RJ45 / Power Jack P5-2.1 mm ID
Power, Ethernet Link, RF RX, RF TX, 4/Channel, and 6/Link Quality
Sub-block error detection and retransmission
SAW receiver filter attenuates cellular and pager interference
Switching regulator
QoS Statistics, Network Settings, Spectrum Analyzer and Firmware Upgrading
Transmit: 1.7 Watts Receive: 0.8 Watts
Power over Ethernet 9-48 VDC over Ethernet - 4/5 positive and 7/8 ground
-40o C to 70o C
175 mA at 9 VDC
140 mA at 12 VDC
35 mA at 48 VDC
170 x 80 x 50 mm; 0.570 Kg
I too would like to see even smaller and more efficient channel sizes, however I do believe the current 5 MHz and 10 MHz channel sizes are a function of the Atheros small channels and Mikrotik has intergrated support into RouterOS for that.
Its really a function of the radio, so I don’t think Mikrotik could even add smaller channels unless a off-the-self radio with those smaller bandwidths (1.25 MHz, 2.5 MHz, etc.) and linux driver support was available.
Cheers