In general I like this plan. It seems a sensible approach. If implemented intelligently, it's flexible and can be modified or extended later. The number of plants is sane (well almost
).
I like the lazy susan idea. I think it would be simple to make and very useful. I might steal it for myself when I redo my cab. My cab is always evolving as I learn more about growing and about how I like to grow. Lol.
Motorized. This is exactly what I would have thought of
and you are quite right its a completely unecessary complication. Rotating the table once a day or every two days should be fine. Bear in mind that on your first grow you will be in the cab ever half hour
You wont be able to stop yourself.
This idea needs solid construction. 8x5ga pots means 40 ga of soil + the weight of the plants and when they are in full flower you will be adding about 40ga of water! Heavy! It may be enough to put the table itself on castors.
I know nothing about LEDs. Nor have I ever looked at CMH bulbs. From your description they sound good. Take into consideration that HPS & MH are well understood by people on this forum. If you ask for advice about a somewhat exotic technology, there will be less help available.
I highly recommend a cool tube. I have a sheet metal vented hood and I am switching to cooltube. If you buy a long cool tube, you can mount two bulbs facing each other, one at either end. You might combine your 400W & your 250W this way.
I have concerns about your lighting pattern.
With about 700W total, you ought to be able to cover a 4'x4' area. Yet your blueprint shows a circle that is 2' in dia. Did I count right?
I think your idea is that the plants should be arranged in a ring and sweep under a succession of lights. The rotation will even out the differences in intensity from the various bulbs.
Think about your 400W sitting above one plant in the ring. This bulb is casting a circle of light about 3' in diameter all of which is prime growing strength. Yet a big chunk of this falls in the center and another outside of the ring where there are no plants. For the 250W bulb this problem is less severe since the useful area is much tighter.
Hole in the middle designs are best suited to vertical bulbs.
When I first started thinking about cab setups, I got confused between pots and canopy. You need to think primarily about the
canopy. The goal is to match the canopy to the area covered by the light. In my current setup, a 600W horizontal HPS I train my plants so the canopy is a flat surface under the light about 3'x3' sq. (I could do more with that light but my closet is too narrow in one dimension and anyway that's plenty for me.)
Using 3ga pots, my plants each need between 1 - 2 sq ft of canopy space. The pots themselves are only 9" wide and I could stuff a lot more of them in under the light but I doubt I will get more dope.
For vertical grows the canopy is made to form a cylindrical surface facing the light.
This depends a lot on what cultivation style you go for and how much work you put into it. Some people just stick the plant under the light and let them grow as tall as they like. Plants grow taller and take up less floor space but the lower regions are not well lit. Others LST the plants to a wider flatter canopy, this requires more real estate but all the colas get evenly lit. The extreme end of this technique is scrog or sog.
You haven't mentioned what your goals are? Personal use? Selling? Obsessive hobby?
If you are selling then yield is a prime concern. However with those lights, even indifferent cultivation should produce 6-8 oz. With effort and attention I would expect at least 10oz , possibly 1lb of manicured harvest. Your next harvest will come 2-3 months after that. How much dope do you need every 10 weeks? So for personal use with a setup like yours, yield is not a prime concern. Sure it's important but things like quality of the high, ease of management and cultivation and the freedom to grow any strain you damn please whether it's a big yielder or not are just as important. If it's an obsessive hobby then practical considerations are irrelevant. If you decide you want to break all records and pull out 3gms/watt then that's what you want to do and there is no arguing about it
Added later:
OIC in your second drawing you do have the 400W in the center. But you have nothing underneath it. For a horizontaly mounted light, the area immediately beneath it is the best lit.
I think you should combine the 400W & 250W either end to end or side by side and have them together in the center. Then, if you are going horizontal, you need to think in terms of a disk of canopy not a ring or annulus.
The LED panels might be nice to illuminate the backsides of the plants on the outer edge.