I haven't ever used a jig like your's, but I have seen them. The new D4R is quite an upgrade over it. Of course the D4R is wider which will allow you to set up a right and left pattern for cutting the right and left sides of drawers at the same time or make a 24" high box with dovetailed corners. The clamping bars are much stronger, the clamp knobs have been replaced by lever knobs which let you repeat the same clamping pressures for multi piece cuts, the D4R has built-in side stops that can't get out of alignment, and I'm sure there are a few more improvements that I haven't thought of. It's been years since I saw a jig like your's. But the method of cutting dovetails on your jig and the D4R is basically the same. If you have the money and use your dovetail jig a lot it might be a good idea to upgrade. If you use it very little, then maybe the new one isn't such a good idea. It's really your call.
Central North Carolina