PLA has been used for metal casting:
http://3dtopo.com/lostPLA/
I haven't done this yet but it sounds like it works great and I plan to try it out.
While the new 0.1mm resolution or a Rep2 should be about equal to or perhaps better than WSF, the fused deposition modeling print method leaves more visible lines than powder printing will, even if the powder printer was actually printing at a lower resolution.
Print software should allow you to increase resolution. You're probably looking for something near .02mm layers which is far better than WSF.
See:
http://www.makergear.com/blogs/frontpage/6591695-20-microns- i-am for an example of .02mm layers.
Any home printer can do this; it is a matter of setting the layer height and adjusting your settings to compensate.
I do recommend a metal cased printer over a wood one, as the metal is better with vibration and not as sensitive to humidity and temperature changes... all of which will really start to affect your prints at superthin layers over very long print times.
When setting up a very high resolution printing profile for yourself, I recommend gradually working your way down from default to tiny layers, so you can more easily tweak the other settings and maintain good quality.
Keep in mind smaller layers increase print times dramatically, and makerbots aren't known for fast printing at default settings. I haven't heard yet if Rep2 has had this addressed, but Acceleration features have been in beta firmwares for the first Replicator, so Rep2 might be faster.
I've never used a DLP resin printer but they do appear to be very high resolution machines by their nature. There have been plenty of kickstarter campaigns but no hobbyists have them yet so I can't speak to their actual functionality but I do intend to pick one up once they've been mainstreamed a bit.