Let me fill you in on my thought process of the big 3 battle (3570, 3572, 3573):
I've read all the debates and after viewing hesalite vs sapphire today, understand all sides now which makes it even more difficult.
I can definitely see what the allure of the hesalite is and it's not just for "moon watch purists". The dome and the the light cast from it are beautiful. BUT, I was surprised how close the sapphire was. Not completely night and day IMO. Also, the sapphire back was not as much of a deal breaker as I thought it would be. The movement is beautiful, but with the bracelet on, the field of view of it is not that great. (looks so much cooler on the internet ;)
So my final answer is... The 3572.50, because it is discontinued and very desirable for good reason--it's simply the best imo. Second would be a new hesalite 3570 and third would be a new sapphire sandwich.
If I bought a used speedy with unknown service should I immediately service it? (on a 3572 it would be at least 9 years old) Do you guys service at regular intervals or let them run until there's a problem? What's the cost of a sapphire crystal vs hesalite? (I'm not so concerned with little scratches, but I have gouged a crystal before)
Thanks for all your help in the threads I've already been through and the info on where to pick up this piece. I'm so close to pulling the trigger I can taste it.