Do you have 2 m total or is this the space for the plant after taking into account the light? This will make a difference on what we advise.
You might want to try LST--low stress training. It will be a bit simpler for you just starting out than scrog, which I personally feel works better with clones. The training for scrog must be started in veg and it is really difficult to cull the males from a scrog ready to flower. It is fairly easy to control the height of the plant if you have adequate light and a good environment set up.
Whether you run more smaller plants or fewer big plants is more a matter of choice. You are not going to want to put reg plants into 12/12 until they are sexually mature, though. Clones can be flowered at any time as you know the sex and they are the same biological age as the mother. Keep in mind that overcrowding plants can actually be detrimental to good growth, so there is a fine line between just enough and too many. I personally prefer fewer larger plants, but circumstances often dictate how you grow. I have successfully grown a scrog in a space that was about 4 sq ft (22" x 28") and 4' tall total during a flowering room remodel.
Like mentioned, you are also going to need some kind of enclosure that you can control the environment. This really is critical to good plant health as you have to be able to control the environment--temps, RH, ventilation, and lastly, but most important, to keep the light out during the dark period of flowering. This space cannot be larger than 4 x 4 or your 600W will not be inadequate.
Have you picked out your medium and nutrients? Do you have a ventilation system set up? We all wish that we could just throw a light in a corner somewhere, but the truth of the matter is that it requires a bunch more than that. If the Critical has caught your eye, you should be able to make that work just fine in 2 m. So, you could get some seeds ordered and get a space set up or look into a tent (probably the best option if you are not handy with power tools and building things) while you are waiting for the seeds. Tell us about the pots, medium, and fertilizers you are planning on using. A lot of new growers make the mistake of starting their seeds in the wrong medium. Basements make wonderful places to grow!