msd digital6+ and tweecerR/T?

I am going to buy a R/T model tweecer by the middle/late part of next month (July) and I have been thinking since the tweecer can controle timing I will build a N/A tune and then build a n2o tune that has less timing, and some other things diff. (the reason I have the digi6+ is for the timing retard). Due to this I have been thinking of trading my digital6+ for a 6a or 6al box. Is the digital6+ that much better of a box that for my needs I still should not go with a 6a or 6al?

Thanks,

P.S. I tried to post a topic on tweecer.oplnk.net but for some reason if I am not on my home computer I cannot post or it gives me a invalid sestion.