For HID lights you want Metal halide for veg, HPS ( not dual spectrum bulb) for flower.
For a 3x3 in veg you can use either a 250w or 400w MH. More wattage is more heat but more light and faster growth.
For a 4x4 in flower you want minimum 600w or 1000w HPS.
Yes they create heat, that is easily dealt with by extracting out of the house. Unless you live in a really hot area where your already at or above the ideal temps without lights on. Then you need to look at cooling.
CMH , a 315 covers a 3x3 and a 630 is lots of light for a 4x4. You can use either bulb for both veg and flower. I would go for the lower K bulb though.
Saying 5 oz per plant is like saying how long is a piece of string, on its own its a good amount from one plant but how many plants were in your flowering space?
I like good LEDs, but if you have cheapish ones then the most cost effective upgrades are in this order.
1, MH-HPS
2, CMH
3, Quality white LEDs.
Any light creates heat, HPS projects more heat downward in the form of radiant heat from all the red - Infer Red.
LED most of the heat comes out of the top of the heatsink.
Both have advantages and disadvantages, heat can be your enemy or your friend.
The key to getting the most out of your tents is lighting it adequately and managing your plants in veg to fill your space.
Often with low end LED the mistake a lot of people make is not having enough light in the first place.
Before changing your lighting you need to ask yourself do you have the ability to properly set up your environment.
There is little point in doubling your wattage and heat if your in a closet with zero ability to get that hot air out of your house and properly exchange air.
