600W HID - Should I get a conversion bulb?

Hi, I have a 600W HPS light on my plant right now. I'm 10 days into vegging since I picked up this clone which was planted in a 4" pot. My question is, how much would I gain from swapping the HPS bulb for a MH conversion? I currently have a 4x2' T5 5000k as a side light, which I'm hoping will add enough blue.

I was looking at this one:
http://www.hidhut.com/catalog/600-mh-conversion-bulb-p-1756.html

Thanks!

Okay, fine, you talked me into it. I'll stick with the HPS with supplemental t5.