I'm intrigued by yor remark that Radisson & Crystal vessels <aren't small ships>. I don't know what the generally accepted norms are for defining ship size. However, I would say that (if using passenger capacity as the criterion) the Radisson Voyager and Mariner (700 pax), the Navigator (490 pax), the Diamond (350 pax) and the Paul Gauguin (320 pax) all might be considered to be "small" ships, especially when compared with today's large and mega-liners.
As for Crystal, their Harmony and Symphony (940 pax) also fall into my definition of "small", although they approach my "medium" category. The right of each person to define ship size -- that's what makes America great!
Seriously, I would categorize as follows:
Very small ships -- under 300 pax
Small ships -- 300 - 1000 pax
Medium ships -- 1000 - 1900 pax
Large ships -- 1900 - 2700 pax
Mega-ships -- over 2700 pax
Obviously, my breakdown is arbitrary. If one defines size in relation to gross tonnage or some other criterion, things would change. In no instance, however, would I consider any of the Radisson vessels as anything but "small".
The smallest vessel I ever cruised on was the Renaissance R1 (700 pax) and I considered it as a small but lovely ship. If you disagree, so be it. I'd really like to see some pros & cons on this subject.