Beta testing should be usable with any mode. It means that someone can use ACME to get certs from the CA, so they can in principle use any ACME client, or any mode of any client.
It’s possible that the CA might ask beta testers to try or use particular modes or features, in order to learn more about how well they work.
I would also love to participate, I work with a bunch of sites both of my own and for clients and I’ve been interested in using letsencrypt to make it easier to add ssl to them than manually managed certs. I’m working through how to use haproxy to detect acme requests and funnel them to a standalone mode let’s encrypt client while keeping all other traffic going towards the main web server for a site so that I can automate the process without having letsencrypt touch my site or understand how to work with haproxy, it also means that anything behind haproxy can work, which in my case includes nginx but also several other unsupported pieces server software, though haproxy is terminating the ssl for most of those. I’ve got at least some modes working for the test ca, but I’d like to run tests against the live one when it’s up.
The moment I see the beta program announced I’ll be signing up.
I don’t currently have ssl (been waiting for LE) so there’s no traffic to it although I do know a few of my users would help in testing from a purely client perspective.
I too would like to participate in pre-release testing of letsencrypt.
I have a number of domains that can be used and will be wanting to test setting up certificates for both SNI and single address web servers. As well as testing certificate revocation and rotation ( revoke and reissue ).
I think the mission of letsencrypt is worthy of my support and I would like to do what I can to make the rollout as smooth and straightforward as possible.
Would be interested in beta test as well. I have a nice mixed configuration with different SSL vendors and intermediate paths right now, and I hope to migrate to letsencrypt.org as soon as it opens to general public.