Gemini (Westmalle Dubbel clone- AG)

Ahoy mates!

Working off a recipe from Beer Captured, trying to more or less make the Westmalle Dubbel. I read in another thread that the Beer Captured recipe maybe is too much on the sweet/raisiny flavor, so my thought is to up the biscuit slightly and up the hops slightly. Slightly drier beer is the target.

What do you think?

Also... they call for a 90-minute mash. Why? Is 60 minutes too short?

Target OG: 1.068 -1.070
Target IBU: 22-24

Malts:
Belgian 2-row Pilsener: 11.5 lbs
Cara-Munich: 8 oz
Biscuit malt: 10 oz
Chocolate malt: 2.5 oz

Mash at 151F for 90 mins (or 60, if I can do that).

Adjunct
Belgian Dark Candi Sugar: 12 oz

Hops
Styrian Goldings: 1.0 oz, 60 min boil

Yeast:
White Labs Trappist

Looking through "Radical Brewing" I see a somewhat different Dubbel recipe. I know there's a wide range in the Dubbel style, but I'm a little confused as to what the components do. The one from RB has:

6 lb pale malt
3 lb Munich malt
1 lb Belgian medium-dark crystal malt.
0.5 lb aromatic malt
1.0 pound partially-refined sugar, in place of the dark candy sugar

1.25 oz Northern Brewer, 90 min

This recipe is going for a slightly lower gravity and a higher bitterness than the one I posted above.

So the things I'm wondering here are:
- What would using a much higher proportion of Munich malt do to the brew?
- What would using aromatic and crystal (vs. Biscuit and chocolate) do?

Both recipes look fairly tasty, I'm having a hard time picking.

OK, we've settled on what we hope is a final recipe, here. Hoping to have a nice rich Belgian but not incredibly sweet/raisiny (which maybe means fermenting a couple degrees cooler than typical?)

5 gal batch

Mash: 151 F, 60 mins
Target O.G.: 1.066
Target F.G.: 1.018 (6.05% ABV)

Malts:
11.5 lbs Belgian Pale
0.5 lbs Cara-Vienne
0.3 lbs Biscuit
0.18 lbs Chocolate malt

Extra:
0.625 lbs Belgian Dark Candi Sugar

Hops:
1.8 oz Styrian Golding, 3.8% AA, 60 mins

Yeast:
White Labs Trappist (WL 500), ferment at 69-70F.

Any thoughts?