dpreview.com is more of a generic and specialist photography site.
In your referral to B&W are you considering photos or just documentation. For photos of high quality you might want a more expensive one that supports "gray" ink cartridges. If you want B&W via using the color mode to avoid the coarser printer dithering to get gray in B&W mode you would probably get a color cast in attempting to get a pure gray scale.
http://forums.dpreview.com/forums/forum.asp?forum=1003
For two sided documents you are looking for a duplex feature.
Presentation quality is lower than photo image quality with poor color rendition and coarse dithering intended for graphs and such.
If archival requirements are not needed go with a printer using dye inks as they are less subject to clogging. Also check out the ink cartridge capacities as you want the larger cartridges to minimize the high costs of cartridges.
Also consider if you need to scan at all and if so spending slightly more for an all-in-one might be best. They also have models with built in home wi-fi connectivity as well as Ethernet and USB.
On a subscription review site I found this:
Canon Pixma MG5320
about $100 US. It is USB and Wireless only, no Ethernet and has a duplex feature at slight quality loss. Photo quality on glossy paper was rated very high. It has a memory stick\limited card reader. It has a second tray for letter size only so I would imagine you could have 4x6 glossy in one tray and letter size in the dedicated tray.
Canon Pixma MG6220 - a recommended printer on this review site.
about $150 US. The quality is a bit higher, has wireless and Ethernet, USB. It can directly print from various media more than the preceding one - CompactFlash, Memory Stick, MultiMedia, Secure Digital. It has PictBridge. It has auto-dulex and also individual color catrs. The only really negative comment was that it was tedious to enter the wi-fi password. I would hope that it is retained.
I mention Canon because I am familiar with its products. These models have separate cartridges for color. Some brands require a combined color cartridge which because of uneven ink use can get expensive. On these two models black is pigment ink and the color cartridges are dye ink. Both are scanners (best for print scanning) and copying as well.
Neither requires swapping the black cartridge for photo work.
Here is the manufacturer's pages:
http://www.usa.canon.com/cusa/consumer/ ... xma_mg5320
http://www.usa.canon.com/cusa/consumer/ ... xma_mg6220
The list prices on the Canon site are much higher than street prices. Amazon has good discounts. Check locally as well if you have a discount store that handles these.
Be sure to pick up extra cartridges. I'm not sure but you may require one workstation locally connected or on Ethernet to see the ink status.