I can't go back to single-boxing, no way. Part of the reason I started multiboxing is because I was unsatisfied with having to look for groups and settle for whatever I got, or join a guild and settle more officially, plus endure the pestering to raid when the time came, and even better, to be gkicked after the odd week or two of inactivity. Leaving all that behind as a multiboxer, I've hit every pre-Outlands 5-man instance without having to LFG a single time, I never have to wait for anyone to show up or worry about anyone dropping, and my guild bank is crammed to the gills and I don't have to beg anyone to send me a tiny fraction of what I've donated to others. Single-boxing is no longer even a consideration for me!