The key to attenuation lies much more in the wort than the yeast.
OK so here's what I've got in the wort department:
2lbs malted Rye
(39 IBU if that matters
1oz Herkules 60min
1oz Delta 10min wp)
projected OG 1.097 and I always aerate responsibly
If I drop an 80% attenuator in there to start with and let it finish, it will leave me with a projected FG of 1.022. I want it dryer though but STILL want the phenols & esters from the particular WLP500. The advice I'm looking for is if anyone that has followed up a ferment with a second fermentation with a separate yeast.
The one I want to use is a diastatic 80-100% attenuator and I assumed, with the primary done, it will have that last 20% of the wort to nom on, getting rid of sugars and drying out the big beer. Buuuuut I'm not a chemist/biologist and have no experience with a second staged yeast (I've pitched 2 before, but this is a bit different) and am worried that the tasty tasty phenol/esters will get wrecked by the second ferment.
A few random comments....
That's way too high an OG for a tripel. The ABV of a tripel depends on a lw FG not a high OG
You have no sugar in there. Not only is it pretty much standard for a tripel, bit not using it 2 I'll seriously limit the attenuation you can get.
With that grist, no matter what yeast you use, you likely won't get the kind of attenuation you're looking for. Keep in mind that the attenuation rating of a yeast is simply a way of comparing it to another yeast, not an indication of the attenuation you'll necessarily get.
My advice is to let this one ride, take what you get, and reformulate the recipe for next time.