In reply to 1philjones1:
Hi Phil - we did it this summer - from memory it took us 4hrs+ albeit we had first come from the Finsteraarhorn Hut up and over the Grünhornlücke and down to the Koncordiaplatz before the pull up to the Mönchsjoch Hut. We probably were a bit slow but in our defence it was a bit later in the day when we hit it the Jungfraufirn having started where we did (as opposed to coming from the Koncordia Hut) and being August there was a good bit of route finding since the was no one path and there were a significant number of crevasses. Great landscape but a bit of a crucible in the heat on the 1000m uphill slog!