I've sailed both these boards a little bit earlier in the season. They are both very nice boards and have equal potential to go fast for different reasons...
The Exocet is a very flat and thin board compared to the 162. Despite on paper their volume's being within a few litres, the Exo feels a lot thinner in the water and some of the top guys (ie, Gonzo) seem to have been using 10.7 as biggest this season maybe because the 12m was sinking the board a little too much (jury is out on that one though). Compared to the 162/Gaastra Vapor boards the Exo doesn't have much concaves and shape on the bottom so it needs all the straps in the back and mast track way back to lift the nose upwind as it sails quite 'flat'. One nice feature is it has a super wide tail (2cm [guessing] wider than the 162) so in strong winds it's a lot more comfortable upwind as you have more leverage against the fin and the nose isn't lifting too much.
Downwind in waves the nose can be a little sticky which occasionally slows the board if you catch a wave whereas the 162 has a very thin nose with V shaped all the way through it so it seems to push 'through' the waves rather than get stuck on them.
The 162 also sails quite flat just like the Exo so you also need to run the track all the way in the back as well as footstraps in the back holes to get the nose lifted. Both the Exo and 162 benefit from having a nice super-soft fin. I haven't tried a lot of fins in these boards (I ride a Vapor) but I did try some very soft Hurricane FRB6's in the 162 and these were working well. A Kashy would do even better if you want to sell your house
Both boards are fast. If you had to choose I'd say you'd have more potential on the Exo is you were <90kg and using 11m as biggest; the 162 should suit any weight rider and takes a 12.5m nicely.