You can do either, there is literally only about a 5% difference in light transmission between the best matte black paint and flocking material. This link has maybe a better option for flocking using an anti slip tape sprayed with flat black paint. The irregular angles of the anti slip tape will be very efficient at stopping scattered light.
http://www.alpheratz.net/observing/ScatteredLight/
I've taken photos through my Skywatcher 80ED to test contrast. Firstly I removed the lens and blackened all the edges of the glass. I took out all the internal baffles for one test photo. With the baffles out I flocked the whole tube for another test photo and finally I put the baffles in and flocked every surface for another photo. All test photos were exactly the same, no difference in contrast.
The lens of a scope will produce a given contrast in perfect conditions. You can't increase the contrast of a lens, you can only prevent the loss of contrast.
I take apart a lot of camera lenses and I tend to use the blackened tubes from them to insert into my extension tubes. I find this works best for maximum contrast and produces visibly discernible results. The tubes are matte black with a lot of ridges throughout to stop scattered light. Knife edge baffles within the extension tubes work well too, don't make the hole to small so that it vignettes the image.
Paul.
