I hauled deep supers about when i was younger, so when it came time to get my own hives I figured going all deeps would be no big deal, until I started lifting them.. I am fully capable of lifting them, but the memories didnt match the reality. I know that eventually I will no longer be capable.. so rather than worry about changing in a few years, I changed right away.
You need 1/3 more boxes, not twice as many, or twice as much equipment. One extra box per hive.. granted, if you have 50 hives that does add up to a lot of extra cost. I can't argue that having about 112 medium boxes in my back room.. deeps would have meant about 30 less boxes.. the advantage is in having all of my equipment the same size. As scatter brained as I am I have a hard enough time remembering my hive tool, much less which frames I need for which hives and boxes, so all mediums adds up to be a real advantage for me.
With two hives, an extra box for each hive is a pretty negligible cost.