Ya all cob led companies say this because there is a very, very small chance of thermal run away.. But that could only happen if if your driving your cobs very hard, and one burns out, then that amperage gets applied to the remaining cobs..and could cause a chain effect, burning out all your cobs.. Yes the 320-1750 is a constant current driver..36v chips..
Ok constant voltage, means exactly that.. The voltage is fixed.. So lets take the 320-54..
What happens. Here is you divide the total available amperage by the number of cobs in your string.. So this particular driver has 5.95amps on tap.. Lets say 6a.
So if you want to run 4 cobs
4cobs ÷ 6 amps = 1.5a per cob..1500ma
6cobs ÷ 6 amps = 1.0 a per cob 1000ma
10cobs ÷ 6 amps = 0.6a per cob 600ma
You can add as many cobs as you want, but your amperage and in turn your wattage per cob goes down, but efficiency goes up.. This works well as you can add lots of cobs to a single driver.. You can actually use the hlg-320-48 for 50v chips.. (I will double check for veros if your gonna go this route) . This driver will give you more amperage to work with. 6.7amps..
Personally i would run 8 cobs in a 4*4 setup.. I do it and works very well.. 3-2-3 design on a 36*36" frame.
But if u want to future proof your system, i would get a hlg-600-54a.. This way you can run 8 cobs now and dim the driver to whatever wattage u want, say 300-400w and when u want to add 4 more chips you can have 12 chips able to run 50w a piece and have 600w on tap, (60-600w)... This way you will have 1 driver powering all your cobs, and even dimming across the whole lot.. Parallel wiring requires more work and a little more complicated for newbies...
So if you want to stay simple, i would run 8 vero29 D 36v and 2 hlg 185-1400's and have 400w...
If you want to be able to change your system around and add or remove cobs later, and have 600w i would go the constant voltage route..
Cobkits owner is running most of his fixtures on constant voltage drivers now and is very happy with them.. Check his site he is selling them, andvthe best price on citizen cobs too...
Cheers