In my humble opinion, for a beginner who is just trying to get experience, the boat is not that important. Since you already have a boat, I would say put your money into a quality paddle, and clothes that will keep you warm and comfortable. I am assuming money is somewhat of a limiting factor, otherwise you'd just buy whatever you wanted. Here are the questions I recommend thinking about when looking for a boat, along with some partial answers. At the heart of the questions, is what you want to do.
1. What is the water like that I will be boating on the most? Big waves, lean towards a larger volume creek boat, local play wave you can hit every day after work, get something more play oriented.
2. Why do I want to kayak in the first place?
a. I saw some guys doing really cool tricks on this wave downtown! - play boat
b. I had a great time with my family on a day long tourist oriented raft trip and the kayakers looked like they were having more fun than us. - down river play/river runner
c. I'm an adrenaline junky who wants to go over waterfalls. - creek boat
3. Am I the type who wants one boat to do everything, or do I like the perfect boat for every situation? If you envision yourself with a multi-boat quiver, buy the Nomad now, as it sounds like a good deal, and you'll buy a creek boat eventually anyway.
4. Do I want to camp out of my kayak? creek boat
5. Do I like to get scared, or do I just want to enjoy the river?
Other couple of thoughts: Most people who get serious about kayaking, go through multiple boats. I think the best thing is just to get out on the water as much as possible, try different boats if you can, and you'll find what you like. I don't have any experience with the Ammo, but it looks like a good boat for gaining experience. It should serve you well in the first part of the learning curve.
I think generally, our culture tends to put too much emphasis on the gear we buy. Good gear is important, but the boat is arguably the most flexible piece of gear. If you just plain want a new boat, that's one thing, but unless you think you're going to jump right into really scary creeking (which would be kind of dumb) you probably don't NEED to buy the Nomad. If big, cold water is in your immediate future, a nice dry suit would probably be a better investment. As a general rule, I would say don't buy a new boat until you feel and understand and recognize the limitations caused by your current boat. As you improve, you'll learn what your boat does well, or not, and that will give you a good understanding of what kind of new boat you want to get. Experience is always a better investment than gear.
Having said all of that, when I got back into skiing after a 15 year break, new ski technology did make a huge difference in my ability to learn Tele. Rocker and NTN made a huge difference. I don't think you'll have this experience with the Ammo and Nomad, unless you're spending a lot of time in really big, boily water, but it's worth thinking about.