I got to take a wonderful video of this at their booth. Wonderful except for the ear splitting audio feedback, so it's completely useless. I'm going back today with my Edge 7 and will try that route.
This version will track up to two gasses and it displays them simultaneously. That's right: the bottom line shows Tm1 and Tm2 simultaneously, No having to switch gasses when you swap from tank to tank. They only use the one sender that has been used by Oceanic for ages. They feel that's been perfected, so they concentrated on perfecting their end in terms of reliability. I really, really like it. No plans to add this to the Petrel II at this point... at least not any plans they're willing to share!