I would think it depends on how many plants you have - what area you would like to cover. And if you are planning on getting more plants...

I feel like the amount of plants keeps growing. But is there a maximum that a particular group of plants can endure without burning from the light?

I don't think you can cram enough t5's into a space in order to damage most succulents. Now if you had some 1000w metal halides that would be a different story.

If anything do you think it would benefit them? I guess I coud also disable some if it was too much.

Just a small note on those lights - it looks like those fixtures have a big single reflector. Fixtures that have a reflector per tube will put more light out the business end where you want it. Since the tubes are round, as much light goes the wrong direction as goes the right direction, so reflectors can make significant differences.

I see what you mean, the ones I posted above just have 1 main reflector, right?

Keith, I have the 4 bulb one, I live in PA, and I have been very happy with the quality of light, my Echeveria are staying compact, everything I have is thriving, I read so much before buying lights I was only more confused, I don't understand lumens and etc. but these lights work great for me!

Keith - I'm using 6xT5HO in a horizontal arrangement and it's not an issue for my succulents.

The decision of 4 vs. 6 lamps depends whether you need or want more light than you already have?

Having a 'brighter' and 'dimmer' set of lights is helpful for catering to succulents with different light requirements (and that is what I am doing).

Many led lights are adjustable with respect to intensity but it doesn't matter those will not be too bright if they were you could just move them slightly further away from plants.

I wish I could hang these lights, but in my apt that wouldn't be feasible.I'm thinking about getting one of those little stands, but the amount of space they cover is too small.