We have the stock 10:1 system on the Infusion. Unlikely to change it ($$), though I like 9:1 myself as it's less line than 10:1. For what it's worth we don't use the cleat either. Couldn't find a spot where it was easy to re-cleat and uncleat, so now it's in a spot where it's impossible to cleat going upwind but can be cleated coming in off the wire during a tack. That is how the pros do it anyway (we are NOT pros but we can try).

My question on the center sheet without a cleat:

1) How does the skipper cleat the main going downwind?
2) Is the traveler still tied/spliced to the end of the main sheet? It hard to tell in the photos.
3) Does the center block interfere with the spin sheets/crew in a wire-wire gybe?