When you get up to 600 Watts (4foot t5(ho) bulbs are usually 54 watts..) there may be more efficient light sources available, like metal halide. At 600 watts any technology available today will generate significant heat (mh/flourescent/led/halogen/whatever). Probably great in a cool basement, not so much in your average house. But, thats a cool fixture. I have one that has only 4 4 foot tubes (54w/t5ho) in it, and its it's about 16" wide. I'm feeling inadequate now. I keep it much higher too, but I have a variety of plants of different sizes underneath, and prefer being able to see them nicely over maximizing their growth. It's still plenty bright enough to flower many plants, including african violets, orchids, and serissa. Haven't had an adenium flower yet, but haven't had any very long and only have 1 that is flowering size. Twisty CFL bulbs are great too, there's a wide variety of sizes available at reasonable prices, and you can use any old lamp you have - clamp lamp reflectors work well, or get creative and build your own fixture out of PVC and some hardware store parts. It's pretty easy to wire classic lamp sockets. (get 6500k/"daylight" bulbs for the most part, no special "grow" magic needed).

I bought a couple of pendants in different finishes at Big Box and held them up to see which finish I liked. (returned both) It really helped. Did the same thing with hardware. Sometimes it's best just to see it.

One plus of the two swagged fixtures is that the table would be well lit across the entire surface as opposed to just the central portion. An elongated fixture will help with lighting more of the table, but depending on the table length, the ends may still be darker than the middle. So then I guess it's a matter of form vs. function dilemma. Also, if cost is an issue, it could be more economical to swag two smaller fixtures than to buy one elongated chandelier. With the right lights, I think it could be done well, but to each his own. : )

But honestly, the pendants really do not do much for the space and they seem a little off in placement, I would probably opt to put recessed lighting there instead. (might already be there and they just put pendants up over existing can lighting...