Single Sparge or Double Sparge question...

I am brewing my first parti-gyle this weekend (two beers from one mash) and I am trying to decide whether to do a single sparge with a mash-out, or a double sparge like I normally do on regular mash.

My grain bill will be 31.5 lbs and my starting boil amount will be 17gals (8.5gals per beer).

That being said... here are two scenarios...

Single Sparge:
Mash 39.5 qt - Strike at 169.8 for mash thickness 1.25qt/lb

Mash-Out: Infuse with 10.5qt of boiling water for 10min - Drain 34qts into 1st kettle for 1st runnings (Pre-boil Target OG: 1.059)

Sparge - Infuse 34qts at 168.6 to raise temp from 164.8 to 168. Drain 34qts into 2nd kettle for 2nd runnings (Pre-boil Target OG: 1.0393)

Double Sparge:
Mash 39.5 qt - Strike at 169.8 for mash thickness 1.44qt/lb
Drain 34qts into 1st kettle for 1st runnings (Pre-boil Target OG: 1.059)

Sparge - Infuse 17qts at 168.6 to raise temp from 164.8 to 168. Drain 17qts into 2nd kettle for 2nd runnings

Sparge - Infuse 17qts at 168. Drain 17qts into 2nd kettle for 2nd runnings (Pre-boil Target OG: 1.0393)

I'm leaning towards the Single Sparge, but I wanted others opinions.

I do the sinlge sparge method when doing partigyle. The main reason is loss of richness in taste as the sparges progress. In other words the first runnings are very rich tasting the second less so, and the third taste like dirty dishwater at times. So I leave out the third since it will only diminish the flavor of the second runnings which is typically what I am adding them too. If I need more gravity I will simply cap with a lb or two of pale malt and other specialty grains

Thanks... I went with the Single Sparge. My efficiency came out at 77%... woohoo!