I have a thread on using the 2800 drums (search for my name and 2800). Bottom line is that some films will can get a line on the back but other films will be just fine. You can always fix and wash outside of the drum. The main advantage of the drum is all in the development stage. I have been doing 8x10 in a 2800 series for about 6 months and have had no problems. In fact I just picked up a second complete drum.
The best way for 4x5 is to get the reels for your 2500 tanks.
Be sure to use enough developer. I'm convinced many 'uneven' development problems can be eliminated by having plenty of developer concentrate in the drum. (not just enough volume, if you know what I mean)
With that setup you should be fine without the expert drum. Save you money for film and lenses