I have a woo ring for my Med here in the UK. I had an email dialogue with them over a spider for the med too. I wouldn't be without the ability to go raised direct. For me this is enough and cost effective despite shipping to the UK. price per utilised cook is probably in pennies after about four years!
If I had a large I would like the Woo / Spider combo but would wonder about the additional possibilities (and complexities) of the AR - these products didn't happen by accident, they have been desired, designed and refined by enthusiasts!
Talk to them, they are amazingly open and helpful.
Wouldn't be without my (med) woo!