Yes, they've taken place every year since 2000 in Sept/Oct, utilising the Jacobite stock and locos at the end of the season. They started off under Bob Branch and ran for several days, then latterly became scaled down to Sat/Sun. One year they hired coaches to take participants from Bridge of Orchy to County March Summit. Last year's ran with the K4 travelling up there specially, and may have been the last one. The locos and stock need to return to Carnforth at the end of the season and this used to run as a one-way tour (see, for example, uksteam.info for 9/10/03 - The Summit Conference). However this dried up and then became an ECS working. However it's been resurrected this year at the end of October by SRPS who are again running it as a tour.
Would be nice to have steam excursions aimed at enthusiasts, with the occasional runpast, must be possible if the will is there. There seems to be too much emphasis on the Premier Dining market these days; however I supposed the flip side of this is that there are therefore more excursions than ever running on the network, so we can't have it both ways!