I don't know why so many people are recommending a DSLR when Reaktor5 makes it clear right up front:
That's right.
Personally, I'd go for a m4/3 camera. Taking your needs and budget into consideration, the camera will be small, light, and will conveniently fit in a small bag! The lens selection is great, as is the image quality. People will point to the smaller sensor as being a handicap, but photography isn't about numbers and technical details. If the image quality is good, and it certainly is very good for Panasonic and Olympus' current models, that's all that matters. After all, Sony made many sensors for Nikon and Pentax DSLRs for years (many of their cameras all used the same sensor!!), and yet Sony's jpegs never turned out as well as Nikon's. There's more to image quality than just sensor size, and Olympus has a better handle on image processing than Panasonic or Sony.
Next, at some point in the future, I'd get one of the very small, fast (large aperture) m4/3 prime lenses such as the Panasonic 20 mm f/1.7 lens, or a similar lens. Prime lenses are fixed-focal length lenses (i.e. they don't zoom), but will generally give you great results, whether you're just doing this for a hobby or not!!

I'm not familiar with m4/3 lens quality, and haven't read reviews, so just keep on the lookout.
Sony's NEX system is also good in terms of the nice electronic viewfinder (EVF) and pretty good image quality, but I hate the lenses. The cameras are very small, but the lenses are huge, which kind of defeats the purpose. Even compared to Samsung or Fuji, Sony's NEX lenses are unnecessarily huge. I don't know if there's a technical reason why Sony doesn't have small, fast primes, or any small lenses other than their 16 mm f2.8 (both too wide, and too slow), but it wouldn't surprise me if nothing was on the horizon.
The Nikon One system is also very good, but I wouldn't recommend it. I've had the pleasure of using the V1 for a short time, and it was nice to use. The focusing is very fast and accurate, while some of the features are really great. To me, the problem is that the image quality of the Nikon J1 and V1 isn't supposed to be as good as m4/3 (Panasonic or Olympus), Fuji, Sony, Samsung, or anyone else for that matter. The lens selection will improve, but I don't know about the image quality. In this case, the small sensor really may have hurt them.
And you can't afford the Fuji X system, which would be my system of choice at the moment.
