Whether the 301's or the 201's will work best depends to a great extend on the room they are being put into and way they will be mounted. At least with the current models, the 301's have a rear-mounted tweeter as well as a rear-firing bass port, and they simply need some space to work properly. When used on the stands (available as an accessory), the 301's can be placed to work very well in a wide variety of settings, but in a smaller room, such as my bedroom, or when actually used on a bookshelf, the 201's performed better. The front-firing port and no rear tweeter to have to bounce off of back and side walls for proper performance make the 201's easier to get good sound out of in many installations.
Again, the nice thing about buying new was that I bought both the 301's and the 201's. The 301's worked better in my main living space, so that's what I kept. The 201's were fine in the bedroom, but I ultimately decided to simply use a Wave music system there, so returned the 201's for a refund. In another place, I wondered if the larger Acoustic Wave would provide better sound and coverage than the smaller Wave music system. The answer was as simple as buying the Acoustic Wave and comparing it with the smaller unit I already had. I preferred the smaller unit's feature set, and it actually sounded better to me than the larger unit. Again, I got a full refund on the Acoustic Wave and used part of it to buy my second Wave music system.
By the way, Bose does not sell returned gear as new, but uses returned items to help stock their outlet stores (after being fully checked at the factory), selling these little-used items at reduced cost but with full warranty.
This probably comes across as a Bose ad, but I really think that many of their products offer good performance at a low price and with exceptional customer support. I've never understood the Bose-bashing that occurs in most audio forums.