When I was boat shopping I looked at several deck stepped designs and I have to say they were pretty sorry. (I was looking for an inexpensive 28 to 30foot boat). Deck compression, sagging deck because the "jack pole" was not adequately engineered, water intrusion from electrical connections, bulging partial bulkheads. Just a bunch of issues. I'm sure most of the problems occur because of differences between what the architect draws and the builder builds. Jeff H clearly states the advantages and disadvantages. You need to look closely at each boat and see how it was done in situ and go with your best choice. The negative about a big piece of aluminum in the cabin becomes a wash when a proper "jack pole" is installed.
I ended up with a pearson 28 with keel stepped mast and am happy with it. The mast is tucked into a nook in the head, seems massively strong and without internal halyards, the only water the mast sends to the bilge is from condensation. I pay close atttention to water accumulation in the bilge to avoid the electrtolysis mentioned above, and for other reasons.
Every boat is a compromise, isn't it?