One size fits all,

[prakel]

I suppose the big question is whether you're set on standardizing on one size box -a tempting prospect, I agree. If you're not 100% set on that conversion then a good combination would be existing BS broods (however many you feel necessary) supered with 16X6 boxes. I never really understand why more people don't super nationals with commercial shallows. They're excellent boxes in my opinion.

You could of course run on ALL commercial shallows thus saving your existing floors roofs etc (with individual brood boxes of probably very similar capacities to langstroth mediums). Myself, I'm running a couple of hives on MD shallows this season but I'm not really taken with the idea to be honest, but that's just personal preference.