I would absolutely NOT suggest the ShortMeg... as amazing as it sounded, it was extremely annoying on the highway or any time when cruise. A constant buzz, it drove me crazy. I have the 4-1 R77 just like you, switched to Brocks SM, then after a month switched back to the R77 (Happy I held on to it) sold the SM.
I can't speak the same for the Alien Head, it is a little milder than the ShortMeg from what most Org members say.
Just my .02c