hi ValleGrown, thanks for stopping by and we would love to have you here at the 600.
Ok, I am not in a tent, but I have plenty of work with 600's...also being European I am kind of just trying to work out your diameters as I type. Okay, if possible go for the bigger one, you will need it, the 600 seems to make you want to cram as much weed under it as possible.
Running a 4ft by 4ft cabinet myself, with 1 600 I would suggest for the tent size at least the equivalent of a ruck125 (5inch fan) I would also recommend to get a cool hood or cool tube, that will help you loads.
I am running 3 lights in my 4ft x 4 ft space, but have a bug fan puling air through them. With one 600, get one fan and vent it and temps will never be an issue.
Let us know if you have any more questions.
Peace, DST