You do, as you are about to tell us.
No, but you do therefore care that you are getting the best bang for your buck (as you have just stated in fact). So (if you had the mind to consider this) ... hearing that Co X have a panel that is 10% more efficient than the ones you might be considering (at the same price) is *exactly* the sort thing you would be interested in hearing. You cannot separate the two.
See, I wasn't working on *just* the comparative figures but the actual real-world figures as well. Sorry if you didn't realise that's what I was talking about. ;-)
Cheers, T i m