That's a good point that the rendering engine is the big thing for PR purposes. I mean, if you said "Wow, we changed the underlying game engine and tightened up performance, our AI is a hell of a lot better now, and you wouldn't believe how easy it is to make content all across the board now!" but didn't change the rendering, people would go "WTF it looks the same what a rip off". Which is sad in a way. Casualty of the push for graphical supremacy, because I know I'd prefer a better game engine.
Though I guess I should note that 'game engine' should be the game engine, not the 'whole engine' if you're going to swap out parts. Then again, considering naming your fancy engine and such is probably only good if you want to market it (either as PR or for liscencing to others), I imagine it's not exactly high on the priority to note what parts are what. Although maybe I'm wrong here, and it was decided quickly what to call it for one reason or another.
Although isn't Gamebryo only a rendering engine? It's fairly versatile, used in a lot of stuff, but the impression I got was it's more like say the stuff RAD puts out, where you tweak it until it's how you want, then drop it atop your actual core game engine. And then, if you change the parts of the underlying game engine, where does it become the next one? With my example of Bethesda, FO3 changed their game engine a lot.. but at the same time it seems they kept a lot the same too, probably to make asset creation nice and familiar. But is it the same engine? Or do they just add a version number and call it a day?
I guess at this point I'd say if you can more or less convert things between them with tweaking needed of course since as noted there's changes and features, it's enough of a similar engine to qualify. Of course, I guess it's also different from the engine coding end, if you can point and say "We just took all this source, and then changed this stuff and this stuff to add these bits in, so it's the same thing just better".. but sadly all we get is the finished product where we can't see all that stuff.
As long as we can manage some level of porting I guess, without having to have the original sources (well, say 3d studio models or whatever you use, xtbls and the binaries made from them kind of are the original material always being compiled text files), it's all good.
And now of course to wait. I'm glad to hear the game is shaping up. I loved SR3, even if SR2 still has a bigger place in my heart, and that sets a good track record. Part of me worries we're falling into hype here and we're gonna suddenly ban people for threatening to challenge that it might not be the most awesome thing ever created in the history of all time, particularly since the game hasn't been released.. but I have a pretty good idea what to expect from a Saints Row game and it looks like it takes that, then cranks it up to 12, because going to 11
isn't good enough.