Re: So why did Ibanez stop using the original Edge?
The Lo Pro Edge didn't solve the royalty problem. Neither did the Edge Pro for that matter. On the Edge Pro, rather than being cast into the metal, it's just a sticker on the sustain block. They didn't stop paying royalties until the patent expired.
You need to look at a bigger picture than just Ibanez to understand the switch from the Edge to the Lo Pro Edge. Ibanez wasn't the only company to develop a low profile Floyd-style trem. Floyd Rose themselves make the Floyd Rose Pro, which is very similar to a Lo Pro Edge.
The entire concept of a superstrat is innovation. Staying with traditional ideas is contrary to the concept. The reason you're seeing the Edge come back is that it's what Vai and Satriani want on their own personal guitars. You aren't seeing it on other models. You'd have to ask them why they prefer it. Vai has made some fairly cryptic comments about it.
You'd have to weigh both trems to really get an idea of how they might behave differently. You'd also have to look at where the weight is on the trem and the effect that might have on how it behaves.