I had never heard of them.. but this is what I could dig up for you real quick. :P
I couldn't find a spec sheet for some reason, and they didn't have it on IceCap's site (duh).
it seems they are just what you said. the only other diffence is they also lack the heat sink (metal sheild looking thing attached to the back) that the 660's have.
I would say its a better deal then the IceCap 660 if you dont use the dimming feature (you could always retrofit a heat sink onto them if you wanted to)
this is intresting to me however. I would think some Work Horses from Fulham would be a killer deal in comparison to IceCap's but they dont have the delayed starting that makes the IceCap's keep bulb life going so strong. Do you happen to have a link to were they sell these URI A4's?
(are the URI A4's repacks from a diffent company? does URI stand for the company's name or is that the "Unified Resorce Identifier" code for the ballast?)
aparently I have questions about this product as well..
I do hope this helps.
good luck with your VHO
by the way.