First of all, thank you for posting the recipe.
I just finished brewing this (6 and half busy hours...), but I'm still a newbie, so I changed the recipe a bit to increase efficiency. This is my 8th all-grain batch, I think, after many extract "kits", so I'm still learning.
Here are the numbers:
I increased the grain by 10% each, aprox.
Mash with 5 gallons.
Batch sparge, and final pre-boil wort was 6.8 gallons.
Pre-boil OG wasn't what I would like so I changed the boiling time to 90 minutes. In any case I dropped the hops at the appropiate times (60, 20, 5)
After boiling I got 5.3 gallons at 1061 OG, which according to BeerSmith is 55% efficiency. I think my mistake was to batch sparge with too much water, but the final measure was around 1025, so there was still sugar in there... Which I honestly don't know how I should have gathered. Maybe my mash temperature was too low (around 145-150F). I though on adding 30 minutes more to mash to give the Pils more time to convert.. but finally didn't do it.
The yeast I used was Trappist High Gravity 3787, as was the only good alternative available.
Anyway, I know this beer will taste wonderfully, even if it ends up with low alcohol, so thanks again for the recipe. For now I named it "Dubbel", I hope you don't mind. I only put names to my own recipes so I don't think I will name this anything special.. maybe some nickname that reminds me it's not mine
If I don't forget about it, I promise to come back and post my opinion here when I open a bottle that aged enough. I of course plan on doing this again, even without knowing how it turned out, because it sounds like a great recipe, so I can re-walk my steps and try doing it better next time. I still haven't brewed the same recipe twice, to compare...