Thanks Rick. I already have a Speed D8 along with this Vybe, so I got the speed side covered. I doubt that the shop's return policy would allow any returns/exchanges; it's been a couple of months after all!
That said, I get regular updates on their inventory, and even if they would let me trade in the Vybe, with the possible exception of one or two single-gear Mu's that may or may not pique my interest, there's nothing in their inventory that I like/can afford at this time. But then again, with its lack of high-gear speed, I am treating the Vybe as a single-speed anyway; most of the time, I just set-and-forget seventh gear and call it a day's ride. But even my cheap Chinese Feida (36-12 single-speed; 20x1-3/8 - 37-451 tires) feels a little more efficient to tool around on.
Which is why a slightly faster top three or four cogs would make this D7 a much more usable go-places bike for me. Given the condition of the infrastructure in this city, the balloonish 20x2.10 tires feel much more rugged than the ones on any of my other bikes (except the Shift 2, which I had sold off earlier.) The guys in the other thread directed me towards this faster
DNP Epoch 28-11 seven-cog freewheel, which should make for a perfect solution. As a matter of fact, if I do this mod and add a cargo rack, I'd probably end up with my perfect daily rider!