You know it's funny I just found this thread.
I've had the EXACT same problems you are having using those drums. I have the unicolor plastic tubes with the one fill end, and the other the dump end. The tube is nearly perfectly smooth on the inside. I use the tubes on the rotor base however, so the agitation is always consistant. I presoak about 5 minutes for each film.
The weird thing is, the developer rotates around the film one directions...but the streaking is always the complete opposite dirrection on the film!!!
I processed over 300 sheets of JandC Pro 100 in Pyrocat-HD 2-2-100 in those unicolor drums on the unicolor base from my Iceland trip, and did not get any streaking. However, I did a few negatives this weekend and the streaking is AWFUL! I really do not understand it. Same film, same developer, same EVERYTHING...just different subject matter images.
Someone suggested that you use a piece of nylon screening on the inside of the tube to slide it in and out. I tried this, and the streaking still happens.
I've tried everything from changing presoak time, developer dilution, temp, development time...but the streaking is still completely random.
I'm sorry I cannot provide an answer for you, as I am seaching for one myself. I'm just going to go back to using trays again for the time being, but using those tubes is great if you do not have a dark/wet enviroment.