I see that there is a Vertical Kilometre race on Snowdon, in conjunction with a Skyrace: https://apexrunning.co/events/snowdon-skyline . But if I was going to be in Snowdonia on 14th September, would I want to spend £30 on the VK, or £5 on the Elidir Fawr race, where there is nearly as much climbing, and also a descent (although for me personally, not having to race back downhill would be one of the attractions of the VK)?

Note to Tindersticks: The VK starts at 12:00, and the Elidir Fawr race at 2:00. You should be on top of Snowdon by 1:00 at the VK race, which leaves plenty of time to jog down the Llanberis path and be in Nant Peris in time for the Elidir Fawr race.