So just an update on my experience.
I wanted to brew a fairly traditional märzen so I brewed a very similar recipe in May of this year and lagered it all summer, finally tapping the keg in September. I thought it was fantastic with some tiny hints of oxidative notes but I was very careful with oxygen ingress. It was also the first keg to blow at my clubs oktoberfest party and was highly praised.
I entered it in 2 competitions and scored a 23 in one saying it was very musty, estery, and carmelly and then scored a 35 in the other the next week and a bronze medal, but also got a comment on the inappropriate caramel aroma.
I used 8oz of Caramunich III in mine, So next time I'm going to reduce the amount to 6oz and go with caramunich I. I'm also not going to lager it so long because I think the flavor really peaked at about 2 months in.