I go that offer too, MissL and will be there in April, although I am already booked under another offer for a VP tournie. I am thinking about calling and asking if they can add it to my existing reservation. It sounds like a great show.
To the OP - it says "get exclusive access to pre-sale Tickets" at 20% off but not sure if that is for all shows We usually just stick to the free diamond shows or show offers instead of buying. This might be one show we will buy tix for though.
MissL - mine is too but I thought it was tied to a room offer, so not sure I can use it with the offer I am already booked under. I will have to take another look at the email as I really want to see this show.