Greetings. I am a Catalina Spas dealer for over 20 years. Catalina Spas is privately owned and is a family run business. The downside is that they do not advertise and their website is laughable. Additionally: They do a huge amount swim spas and has pretty much backed off their hot tub side. It doesn't mean that the spas are garbage. I am a huge fan and I like their quality a lot.
The CL1400 is going to have the least amount of jets and is more "entry level." Plus its kind of boring.
The Quebec/Montreal are two sides to the same coin: One is all bench seating and the other has a lounger.
The Neptune is going to have the most jets but I'd encourage you to get the 1.5HP Warm Air Injection System (aka BLOWER) as its able to give you a nice boost for only a small cost. Also- As it has 65-70 jets, some that are 5 1/2", you'll need the extra motor. In fact- I'd really push you to do the blower in any one you may buy. It's a reasonable investment and has a tangible result that you may like long-term.
The knock on the Neptune is it has some seats that are very deep. Sit in it and make sure you'll be comfortable. If so- That is the way to go.
The Neptune, Quebec & Montreal are fine in the SOLO models. If you go PREMIUM then you're adding additional LED lighting (not a big deal) and audio, and it will probably run $1000 extra. I do not see that being a good return on investment.
The standard LED lighting, LED waterfall and ozone should be included. He may say it is something he is throwing in. I assure you, he is not. It is the only way it comes.
The pricing you are getting is reasonable but I don't know if it includes delivery, chemicals, etc.
I hope this helps. Good luck moving forward.