I've been watching for the past few weeks because I knew this was coming. The 3/5/79 show (seen on 6/5/05) was the first played to 300, with the 11123 format. The 3/19 show was the first with the 11223 format. I don't know when the daytime show went back to 11123, but I know from watching that it was still 11223 in the spring of 1981, but the TV Favorites special that recently aired on a Saturday night was from 1983, and it used 11123.
I like 11223 better for two reasons:
1. The face-value questions are, counterintuitively, more important. Sweep the first three questions and you usually win. Under 11123, if you get two of the three singles, the third is unimportant.
2. Symmetry. Teams that are evenly matched, by definition, are likely to split the first two and the next two. Under 11223, such teams will have close scores.