That's a common misunderstanding-- in the 'old' days, having 'b' devices merely present forced 'g' networks to slow down to be compatible, but 'n' and 'g' are much more compatible. When a 'g' device is connected but not actively transmitting data, the 'n' device is virtually unaffected. When the 'g' device does transmit, it sends at the slower 'g' rate, but properly shares the airspace, so when the 'n' devices do transmit, they are at the their full speed. In that respect, having an additional 'g' device isn't all that different from having an additional 'n' device. If you have a couple of each, you'll hardly notice a difference. With more devices and/or heavy data transfer, you might start noticing a difference.
Please note: this is only when you're using the 2.4 Ghz radio -- the V-M200 is "dual band," but not at the same time. If you set it up as a 5 Ghz AP, only 5 Ghz-capable devices can connect, and then only at 'n' (and often 'a') speeds.
