Dude... I fucking hate ebay for this kind of stuff. I urgently advise against it. I bought a supposedly new ballast, dead 2 days later, guy dissapered, at the same time I got a supposedly new bulb.... My plants SUCKED until a few months ago when I bought a NEW Hortilux at a grow shop... That bulb from ebay was not new, it was dim as fuck from start, but I didn't know it cause it was my first bulb...
When my first ballast stoppped working I took it to a grow shop, it ended up being the fucking transformer, wtf. I bought a new ballast, with a 3 year warrenty, from them imediatly. Guess wut? the cap died in it a few months later, I took it in and they replaced it right then for free no questions asked.
So my point would be... This shit is expensiive and it seems to fuck up allot. I see that its from HTG supply so their probably not going to fuck you and honor the warrenty. BUT your spending $150 with shipping, you can get the same setup at a hydro shop for that and then be able to get it fixed imediatly if it breaks instead of having to PAY to ship it back to them and WAit while they fix it, while you see your plants die...
If ya dont have a store then obviously you have to order and imho that sucks...
Online is great for cheaper nutes, cloning supplies and some other things, but with something as crucial as your flower light I just dont recommend it.
I just havn't had good luck with online shit at all and with shipping it usually comes out to the same price. I did get a 400w MH ballast kit (cap, transformer, mounts...) from 1000bulbs.com, it was $50, with shipp, and I allready had an extra batwing reflector, the case and wiring to my first ballast, just needed socket and bulb. I was also broke, as allways. Guess wut about that thing? The cap is dying... So I've got to get a new cap now, from store, still just the transfomer for that price is good and it WAS brand new.
Hope that makes everyone think before buying online... Besides the fact that everything you do is watched...
As far as the light arrangment yea have 2 areas if ya can and if not, maybe if those where the 54w sunblaze t5's like I have you could put 2 on each side it it would help, they dont use much elect. But in your case just use the hps.
You really need to stop thinking like "how much extra am I going to get if I do this or that" Just grow your plant, learn, do it better next time. But to answer ur question probably no difference with those small lights added, Now if you added a 105 watt CFl(20 bucks from 1000bulbs.com on each side it would help, btw cool light, 5000k+ for veg and warm light, -3000k for flowering if ya didn't know, u said you had 2 warm and 2 cool lights, they would be better for veg if just cool.
All my opinions
Hope I helped with something
Like I should.