What is more important - how we start or how we finish?

As alluded to last night I have been busy doing some opening prep for a couple of important club games. One of the games was played tonight, and had a very curious finish. But I'll get to that later.
What I had prepared for the game did not come to pass so I am happy to share it instead. My opponent was a Trompowsky player so I looked at a line that goes 1.d4 d5 2.Bg5 Bf5!? Now if my opponent plays anything other the 3.c4 I would just play c6,Nd7,Ngf6,e6 and have a nice solid position. It turned out that after 3.e3 c6 he went for the bishop swap with 4.Bd3 and the game took a different path.
What I was really hoping for was a line that went 1.d4 d5 2.Bg5 Bf5 3.c4 Bxb1!? 4.Rxb1 e6! If 5.Bxd8 the Bb4+ wins back the queen with equality while if white ties to get cute with 5.Qb3 then 5... Qxg5 6.Qxb7 dxc! opens up a whole of pain.
But none of this happened, and at some point I overlooked a combination that gave my opponent B+N for a rook. So I dug in and tried to stave off the worst. To make progress my opponent began swapping off pawns, but failed to realise the danger. As more pawns disappeared I was able to get my rook active, and eventually got to a position where I offered my rook to reach a KBNvK ending! Fortunately for me my opponent did not know how to force mate, although he did know that he did not know. So he tried to hang on to his last pawn, but after avoiding some small tricks was able to give my rook up for B+P, reaching a clearly drawn ending.
The question that was debated after the game was 'Is it worth knowing this ending?' I would say yes, but my opponent felt that his time could be spent improving other parts of his game. I think there is merit in both arguments, so maybe it comes down to personal taste.