My first indoor grow with the basic full spectrum 1200w mars 2 version. You can check it from my sing link.
I used them for 3 plants so far 1 of them got cut soon (RIP), One will be finishing next month hopefully with alot alot alot of problems PH mostly. and one new born think diferent that it started from seed under the lights
So here is what I am sure about that lights.
1)They need to be at least 1.6m from the floor of my cabinet to cover the whole of it without I notice any plant
stretching. 1.5mx0.85x1.8m cabinet
2) Today I lowered them 35cm above my flowering Auto Durban Poisson(ADP) And hardly covering the whole plant so I ll update on the results later.But the small think diferent show some stretching towards the lights after 10 hours allready
3) After the plants have established a strong root system and start drink some descent amout of water 1-2l per day I lowered the lights at 60cm over the top of the plant and raising it when the plant was at 50cm.
As a result I have a fluffy/leafly bushy plant right now in flowering that was kept under 1m (70-80cm right now at day 50).
4)I do beleve even with toping I wouldnt had achieve that results to keep the plants short with that many tops.At least i didnt went I tryed it outdoors.
5)Giving that infos I am going to install a scrog pannel to my think diferent to keep the plant really short and the lights at max distance to see how they ll work!Cause I have a slight feeling they work better if the distance is bigger.
Alaso the 1200w version Does emmit heat yes yes it does!!! never tryed 600w HPS but for my winter grow the mars2+RVK 200m and I ll be ok and without gas bill for my heating
And try not to laught hard with my enlgish please

I do try my best!