3D printer advice ~$3000-$4000 range

[curious aardvark]

You haven't mentioned the maximum size of the parts you want to print.

pretty much all printers will fit the other criteria.

But in the sub $4000 range their are some really cool candidates.

from the multi material Hyrel: http://www.hyrel3d.com/
to the 3d photocopying magic of the Zeus:http://www.zeus.aiorobotics.com/#!buynewlayout/cvsd

Or the Builder series with their two material one nozzle approach. http://3dprinter4u.com/?gclid=CjwKEA...xQRRoCYHDw_wcB

For that money you're in the sweet zone of quality light industrial machines.
Which also means there is a ridiculous amount of choice.

So have a look at the three very different brands I've linked to and see if that sparks a better idea of what you're after :-)
Personally I'd love any of them, though for sheer versatility and build quality I'd lean towards the hyrel - but a copier with 0.15mm scanning resolution - ooohh that's tempting and the builder nozzle would solve every single problem I have with dual extrusion.

Even with just those three - It would be a ridiculously hard choice.
But hyrel could add a clever multi-filament nozzle at some point and a scanning head - so, maybe that might edge it lol

plastics wise - I'd go pla or pet. Abs has just too many hassles - smells, shrinks, doesn't stick, cracks will never be the dimensions of the original model without resizing before print etc.
I haven't tried pet yet (got some, just haven't had time to try it) but by all accounts it gives the toughness (I did do a bend test and it's way tougher than abs) of abs with the ease of print and lack of shrink of pla.

But there are so many different varieties of pla now on the market, plus it depends where you live for what they cost. At the moment the states seem to have the best choice of premium filaments, with us foreigners having to pay exorbitant postage to get hold of it.

But hey, that's life :-)