After careful consideration, I've decided that we will be using a traditional attack roll / damage roll mechanic -- the idea I proposed was just a trial balloon I wanted to float to see what people thought. With a change this huge, it was going to need to be a clear favorite among all patrons (and me!) for it to be the standard; clearly, that's not the case, so we're keeping the original in this particular case.
For what it's worth, things like critical hits are still a little more up in the air because there's a lot of room for tinkering there without radically changing so many other mechanics.
Also, there will indeed be special effects that come into play with good attack rolls, but rather than that being a universal mechanic that happens everywhere, it will be something that particular talents, enhancements, and the like bring into play. Even though it won't be universal, the structure
will be, so whenever it comes into play, it will be easy to remember when special effects come into play. (In other words, it will be fairly similar to several different Saga talents/Force powers/etc. that have higher damage or whatever kick in for every 5 points your roll is higher, or whatever.)
Given all this, I think this topic has served its purpose and run its course, so I'll be closing it. Expect to see some different (and more focused) topics eventually on some of the things I mentioned above, probably once we're past the deadline and the patron-only forums are rolling.