OK!
I spent a late morning and most of the afternoon on the singletrack on an estay so feel I am qualified to comment here.
Estays are crap! I constantly hit my ankles on the stays, they're covered in bruises. Estays are the very contrivance of satan, yes quick on the uphill sections but nervous as a virginal choir boy on his first visit to a brothel on the down hill. To compound the issue all retrobikes and retro components are impractical and poo! I had no grip from my retro tyres, my retro cantis were rubbish and offered little stopping power, the rigid forks just made me feel every bump and bounced me over them rather than give me any traction, my crap retro seatpost kept coming un-done no matter how tight I did the saddle rails up, my front mech clogged with mud and jammed me in granny gear for three hours (don't worry Heathy I've given myself a dead leg as a pennance), my rear mech clogged with mud and kept skipping, bloody 28t biggest cog on the back...
In summary estays are rubbish as is all that is retro so I vote cool as the sum is all bloody good fun!