I am also using the AB34 in Anderson flats for my seedlings. I need to buy some more for next year. I am also using the next size up (ab35 or ab36) for the larger saplings to continue growing. I think the 35/36 bands will be the last band before putting the seedlings in grow bags or pond baskets.
My seedlings have done well with band pots so far. I have yet to take one out of the pots to see what the results will be as I been using them for less then a year.
Fair warning on the bands. If you have a perfectionist streak you may have some work to do once you get them. Almost all of mine came with the injection mold nub left on that pushed the center of the band inwards and prevented them from standing up by themselves. I ended up using my concave cutters to cut the nubs almost flush on probably about 200+ bands.
I love the quality "feel" of the Anderson products, but I do wish their injection process also removed the nubs afterwords.