I did this trip a couple of years ago and it was amazing. The boats are vintage boats with a Croatian captain and staff. Most companies use the same supplier in Croatia so the boats are all very similar. The boats Topdeck use do differ in size, anything ranging from 18 to 30 people per boat. The know the one boat is smaller but it has en-suite bathrooms. I was in a bigger boat in a below deck cabin and it was absolutely fine!
You are barely in your room so it doesn’t make a difference. You wake up and you are sailing the Adriatic. The decks are spacious and scattered with loungers and chairs and you relax and tan all day. The boats stop in coves and spots throughout the day and you jump overboard and swim and relax on lilos. Then each night you stop in a different spot and go for dinner and drinks and meet people from the loads of other boats that travel the same route.
I would definitely recommend it!