Three Pawns Or A Piece?

WHICH is stronger?
As with most things in chess, a lot depends on the position.
But generally the consensus is that a piece is worth more than three pawns in the opening and much of the middlegame, but the pawns become stronger in an ending.
The situation arose today as early as the 20th move in my round-seven game from the Bad Wiessee Senioren-Cup.

Black to make his 20th move in Spanton (1880) - Werner Mattgey (1766)

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While it is true to say White has three pawns for a piece, it is more precise to say White has three pawns and a dark-square bishop for a pair of knights.
White also has the bishop-pair in a position with diagonals for them to work on, and more space.
Both players have an isolani, and White has doubled c pawns.
Komodo9 gives White a slight edge; Stockfish10 at first gives Black a slight edge, but soon changes to dead-eye equality.
20...Ng6
This prevents the annoying 21.Bf4, but the knight will become a target for White's kingside pawn-advance. The engines suggest 20...Na5 or 20...Kf7.
21.Kf2 Nce7
Stockfish10 much prefers 21...Nd8, but Komodo9 comes to prefer the text, and also 21...Na5. I guess it shows just how difficult these unbalanced positions are to assess, and to play.
22.Bg5 Kg7 23.h4 Ng8 24.h5 N6e7
Black has not done anything so very wrong, apparently, but by now both engines reckon White has the upper hand.
25.Bf4?
Careless. It was better to bring up the king, which will almost certainly be needed anyway to force home a pawn.
25...c6?
An automatic reply, but it makes his bishop bad and, more importantly, misses a chance to get rid of one of White's pair of connected passed pawns. Correct was 25...Nf6, when 26.Bd3 (or 26.Kh3) Nxh5 27.Bxc7 greatly reduces White's advantage. Worse is 26.Be2? Nxe4+, while 26.h6+ only preserves the h pawn in the short term.
26.g4 Kh7
This hardly helps, but it seems Black is lost whatever he plays.
27.Kg3 Nf6 28.Kh4 e5?
No better is 28...Nxg4? 29.Bg5.
The text hopes for 29.Bxe5? Nxg4 (although White is still better).
29.dxe5 1-0
On a brighter note, the sun came out this morning. It is starting to cloud over this afternoon (it has just gone noon Berlin-time as I type), so if I intend to go walking, which I do, I need to get started asap.

The venue-hotel early this morning, with snow-capped Bavarian alps in the background