@jkarp, the text could still transpose into the Benoni. 1...Nc6 is actually one of the few lines that *cannot* be the Benoni, because the key move in that opening is Black's ...c7-c5. 1.d4 Nc6 is just the Queen's Knight Defense.

This can still transpose in soo many openings: Queens gambit, Slav, Benoni, Catalan, Tarasch, etc.

A 2200 player will know how to handle Nf3. But your idea is sound, better avoid the Grunfeld if you dont know much about it.

I would avoid committing to the fainchetto until white has committed a centre pawn to the fifth rank. Best is ....e6

The move g6 is well-known and solid. Black has a good plan, which includes c7-c5 and Bg7 to undermine white's center.

Black would possible play Nh5 to obtain the Bishop pair down the road

I have to admit, ...Nh5 is not the sort of thing I like to play. However, had White castled now, 6.0-0 Nh5 would have picked up the minor exchange (Bishop for Knight), and after 7.Bg3 Nxg3 8.hxg3, there would be a half-open file there that White will find hard to exploit.

Then again h3 wastes a tempo. I feel white is already taking a defensive stand here, leaving black the initiative.

Not just to gain space. Black get his pieces working in harmony against white's d4 pawn.

Very good move by black trying to open the center while the white's king is not yet castled.

Because Fianchettoed Bishops are bad in close pawn centers. If the center is opened up, the DSB gets stronger for Black. I want to avoid that and keep the center closed to my advantage

@jkarp - he doesn't want BLACK to have it - not unchallenged at any rate.

The bishop on g7 is looking at granite rock. Defensive, but not a bad idea.

This is where rating differential can have a bearing upon decisions. Against an opponent nearer his own rating, Black probably would have exchanged. Here he accepts a small risk in the hope of generating a more dynamic situation.

My guess would be to open up a potential maneuvering space for the Nf6.

Maybe Black was concerned with certain possibilities associated with a WN on g5, and Black's Queen, and perchance the LSB as well, operating down the a2-g8 diagonal. This prophylaxis obviates any such threat.

Sounds like a plan.

Was White hoping for 13...Bd7?? 14.Nxg6... ?

Possibly 15.Ba6 and then 16.e4 was the way to go. The difference? After 15.Ba6, the c8-Rook is induced to move off the c-file, leaving the Q hanging. Then 16.e4 cxd4? 17.cxd4 and 18.d5 is a dual threat: to fork N and B, but also to attack the pinned c6-N. It appears from that that e4 was broadly the right idea...

The original plan was a2-a4-a5. What changed? What is the point of Rfc1 if you now go for a center break? If you have a plan, then stick with it (unless something really better comes alaong).

There was a very intriguing line that involves a sort of Q sac by Black: 16...Nxe4!? 17.Qxc7 Nxe2ch 18.Kh1 Nxc1! 19.Qxe7 Nd3 20.Kg1 ...(Not 20.Qxd6 Rfd8! and Black has much the better of it) 20...Rc2 after which Black's active game must be worth the slight material deficit (e.g. 21.Nhf3 Rfc8)