i've been using disposable tubes for over a couple years now and after trying various styles, i've switched to eikon's single piece tip/tube disposables. i tried to get use to the weight/balance/vibration issues with straight up disposables, but in the end found that a ss grip made all the difference for me. it gives you the weight/balance that your use to and cuts out the vibration you get from plastic. as for the grub screws cracking the plastic, with the eikon ones, they will dent in if you tighten them down too much causing your needle bar to rub. it doesn't take much tightening to get them to grab enough so that they won't budge. alright...enough of the background, on to the topic. i get the fact that your not going to have any metal wear, but i think that scrubbing tips is the worst, time consuming, most meticulous part; so why would you want to scrub plastic tips, let alone tips at all? if your looking for disposable tips, why not get rid of the tube as well? one less thing to scrub and autoclave the better.