Everything is a trade off. If you go to all shallows, you have all of the disadvantages of the mediums but even more so (more frames to buy and build, more boxes to buy and build) and the queen has less open space to lay in. But you would save some weight. However, I find the eight frame mediums are just the right weight for me, and just the right width for the cluster to winter and just short enough that the queen will easily move to the next box. So build a few more frames and boxes is worth saving money on back surgery and having my hives overwinter well.

If I had all eight frame shallows I'd be tempted to pick up two of them all the time because they aren't quite a load... but two is a little over...