I have noticed a lot less difference in prices between a later Egnater and the Rocktron versions of similar products. The older IE4 seem to get more and more money and even the Rocktron IE4 seems to be going up in value. I think in general the Egnater name has grown and is increasing in value and stature over this last year or so. There is essentially no real difference between them. I believe a read a post on the old Jared Coberly forum by Bruce where he said that the perceived difference was because of pot values, so that when set side by side at the same settings they sounded a little different because the values were not the same. The tone? Still in there. If I were buying those models I would look for Rocktron versions just because they are a slightly better deal. Of course long term investment the Egnater will cart the boutique mystique further and probably gain in value at a higher rate so re-sale wise they would be the better deal. But I just like to get a good deal on great tone so ...
My observations are based on eBay sales BTW.