I think I can answer several of your questions.
1. Concerning the 3D quality on the 640 – there seems to have been a software problem with 3D. From what I have seen here, Mitsubishi has released updated software for this. I think it is available from the Support section of the Mitsubishi web site. People here say it works well.
2. The 3D menu for the 640 is divided into features:
a. “Source Format” is the controls of the internal 3D adapter.
i. OFF is for no 3D even when you have a 3D signal.
ii. AUTOMATIC is for a 3D signal that matches the HDMI 1.4a standards for the Mandatory 3D signals.
iii. SIDE BY SIDE is for s-b-s 3D signals in 720p, 1080i, 1080p/24Hz, 1080p/30Hz, 1080p/60Hz signals that do not perfectly match the HDMI standards but are still available from cable boxes, satellite receivers and other sources. This is a manual setting. Also any 3D signal that would trigger the AUTOMATIC will override this setting.
iv. TOP/BOTTOM is for t-b signals in 720p or 1080p/24Hz that do not perfectly match the HDMI standards but may still be available from cable boxes, sat receivers, and other devices. This is a manual setting. Also any 3D signal that would trigger the AUTOMATIC will override this setting.
v. CHECKERBOARD is for 1080p/60Hz checkerboard 3D signals from external devices such as the external 3D adapter and several computer graphics cards/3D programs. This is a manual setting. Also any 3D signal that would trigger the AUTOMATIC will override this setting.
vi. 2D + DEPTH is to a 2D-to-3D converter of sorts. Gives standard 2D signals a 3D or depth quality and does require the glasses.
b. “Glasses Emitter External” are the controls for the 3D glasses synchronization emitter you plug in to the back of the TV. Standard is Left eye first, Right eye second. Reverse is Right eye first, Left eye second. This just adjusts the synchronization of the glasses – some glasses and some original source material may be the reverse of what most use for standard.
c. “Depth” controls the amount of depth you see in the 2D + DEPTH conversion process.
d. “DLP Link” are the controls for the DLP Link glasses emitter internal to the TV. This one has the OFF setting because when it is on you get that color shift you complained about in your C9. DLP Link type glasses use a special bright flash added to the picture. It is this flash that causes the color shift. Most DLP Link type glasses filter the flash out and the 3D picture looks correct, but the glasses that use the other type of emitter plugged into the back, often do not filter the flash and still show the color shift. If you are not using DLP Link type glasses keep this set to OFF.
3. I know you asked which are the best glasses; however there is no universally excepted answer to this question. It highly subjective. When used properly all off the glasses have good to excellent performance but the criteria of “best” also includes weight, size, color of lenses, replaceable vs. rechargeable glasses etc. and everyone have different opinions.