Let me preface my thought by saying I haven't rode the Swift on rides mor ethan around the neighborhood. I might end up selling it because I need the cash which kinda sucks. Also keep in mind the mini velo I have is one 4 prototypes and so its a bit different from the ones bikes direct has now. I think the geometry is pretty similar though in general.
The Swift is a very nice bike and by far the nicest folder I have ever actually ridden. Its a nice bike, but I guess the breakdown is why I like my mini velo better.
I like the relaxed seat tube of the mini velo better. It also has a lower bottom brakect as well which I seem to like alot. The Swift's bottom brake is around 3/4" taller part of that could be tires, but its a noticeable difference. All this I think makes the Mini Velo seem a bit more stable to me. People like different things though.
Mounting a rear rack on the minivelo is as easy as buying a rack and putting it on or in my case pull one out of my parts pile. If I was determined to keep the Swift I am sure this is a way to put a rack of some kind on the bike, but I am not going to worry about it at this point. I am sure there is something that could be done.
The mini velo comes with drop bars and more speeds. I toyed with putting a Sora group on the Swift and some cantis, but thats not going to happen now. I like the downtube shifters on the mini velo so I don't feel the need to upgrade them, but if that was something you want to do both bikes would need some money for that.
Both bikes look cool in there own way, but I like the look of the mini velo more. The Swift is a nice looking bike.
Whats good about the Swift?
Its a high quality bike and its worth the money. The Mini Velo is a budget bike, but at the price you get you can spend some extra money if you are at all picky upgrading it. My Shetland was speced nicer than the current Nano with a couple areas here and there.
V-brakes or canti's I would prefer these and that part of why I was interested in the Swift. My prototype also has 451 wheels and the tires are more narrow than what the Nano can fit.
The Swift folds. =) When I took the mini Velo to Minneapolis a couple weeks ago on a trip with the wheels off fit it easily in the trunk of a 2007 Hyundai Elantra and plenty of stuff fit in around and on top of it.
The Swift has a longer wheelbase than my minivelo, but I don't know if its much longer than the Nano.
Its probably a bit lighter than the Nano, but not by a great deal.
Whats the bottom line for me? The Swift is a nice bike, but there is no question which bike I would keep even if price was no issue. I like the way the mini velo ride and it fits me well. Then there is the question of cost and its more narrow for me. The Mini Velo was $240 shipped to my door. The Swift was lightly used purchased on craigslist for $400 which I think was a pretty good deal and why I purchased it in the first place. If you are looking for something to ride primarily in a roadbike vein and don't care if it folds I would go with the Mini Velo. If you want to save a few bucks you can get a black one from bike Island for $250 with some scuffs on it. If you want something that folds and want a higher quality bike and don't like super relaxed geometry get the Swift and convert it to drop bars. I have one I'll sell you. =)
Feel free to ask anymore questions that would help you pick. I know I am biased toward the mini velo because its probably my favorite bike I have every owned and I have ridden it a decent chunk of miles and the Swift is a new bike and other than putting on a longer stem which helped I haven't been able to take the time to get it really set up the way I would want it.