We only use the disposable blades both for mictrotomy and  the cryostat
because they are much safer and less time consuming than having to sharpen
blades.  I prefer the low profile and my co-worker likes the high profile
blades.   We use the same blade holder. You may have to tighten the screws
slightly with the low profile but I have no problems doing that.   I think
the best we have ever found are the Accu-Edge.  They cut thin sections and
stay sharp through many blocks as long as you don't hit bone or calcium,
but that goes for any knife.  I don't know what the purpose would be for a
medium profile blade.