Good information so far, but I'd add a bit.
Picking nits: the Voigtlander secondary shutter is grey, not white. It's there because the shutter design is adapted from an SLR shutter, which relies in part on a mirror to be completely lightproof.
The effective baselines for different Cosina Voigtlander models vary. The T has a nice long baseline, and the R3A a longer effective baseline than the other R series. See cameraquest.com for accurate info on rangefinder effective baselines for the new Voigtlanders and many of the Leicas. The info is spread around, and some of the superlatives; longest baseline, fastest lens version, only 40mm lens, are out of date as newer Voigtlander models come out.
A cheaper older Leica may need a CLA to shoot in spec, and a CLA may be the price of a used or new Voigtlander rangefinder. Leicas are better made, and will last longer. Voigtlanders vary noticeably in ruggedness of build. See cameraquest.com in that regard. Lower quality in the R and L bodies, better in the T and R2, and perhaps even a little better in the R2A and R3A. I'd call the T decent quality, the R2 fairly rugged, and the R2A/R3A very solid relative to most other makes.
M2/M4 will require a meter, Voigtlander makes a nice one for the hot shoe, or you can buy a Leica meter or handheld for them. The Bessas all have good accurate meters built in, reading off the gray front shutter.
I really like the 1:1 finder and focusing in the Voigtlander R3A, but I also like the R2 and T a lot. The T needs auxiliary finders, and the R3A has built in finder frames only out to 40mm. The R2 and R2A will get you out to 35mm with built in frames, but have shorter effective baselines.
If you want to buy an RF that your kids can use in 50 years, get a Leica. If you want to save some money and have a shorter life expectancy in an otherwise sound and well built camera, look at the C/V Bessa T, R2, R2A, or R3A. Cheaper and less well built, but still servicable are the L and R. Most of the C/V lenses are relative bargains. Careful reading at cameraquest.com or online searching of reviews by Erwin Puts and others will tell you about the lenses. I'm particularly happy with the 75mm f:2.5, 21mm f:4, and 15mm f:4.5 that I own, but others that I don't own get great reviews as well. The wider C/V lenses include auxiliary finders in the price.
Best places I know of to buy C/V new would be cameraquest.com and perhaps photovillage in the US, and I hear good things about Robert White in the UK(oGBaNI). Used Leicas are all around, and prices vary, but I have no good ideas for UK purchases. A "bargain" used Leica from KEH could be a very good shooter. It looks to me like the new offerings from C/V and others are driving down used Leica prices over the last couple of years, especially on bodies.
I've heard the reported problems with UK official Leica service and prices. There are several good independent Leica repair services in the US. Perhaps someone on the list can refer you to a good independent UK service person.
CVUG, Cosina Voigtlander Users' Group, subscribeable from cameraquest.com is a good place to ask questions and browse archives on new Voigtlander equipment.
OK, so perhaps I added more than a bit. Hope this helps.