It switches between the two? It doesn't manage traffic across both connection at once? This might work if you have a backup 3G/4G connection that you must pay to use per the amount of data transferred, but if both connections are "unlimited", the device should use both.
Also, 64 clients? Is this wireless clients, or total clients? I mean, I have 8 clients at my home for two of us (2 cell phones w/ wifi, Wii, 3xlaptops/netbooks, Nook, 2x desktop/dvr PCs). Yeah, not all 8 at one time, but seriously, a business could rack of 64 simultaneous connections pretty fast.