ext/couchbase and persistent connections

I was wondering if I could get a little more information about of ext/couchbase.

A little background, I've been using Membase/Couchbase for about a year now as part of the backend for social games. To date, we've been using PECL Memcached on our app servers that connect to a stand-alone moxi proxy that then queries our Membase cluster. I've been looking into replacing ext/memcached with ext/couchbase, but there's a couple questions I haven't been able to find yet.

The first is would it be feasible to replace ext/memcached and the stand-alone moxi with just ext/couchbase? I know that ext/couchbase is a smart client and I get the impression that it does the same thing as moxi: do an internal lookup of the vbucket mapping and route the request to the correct server. Does that sound about right?

The second question has to do with persistent connections with ext/couchbase. In theory, I'd like to be able to open a connection, perform x number of get/sets, and then when the script finishes running and exits, the connection is closed/destroyed. I know that persistent connections are supposed to help with performance/resource usage (all good things in a social game setting), but I need to make sure I'm not going to run out of connections when there's high usage across a wide user base. So my question I guess is when exactly does a persistent connection get closed? Does it persist between script executions? Or does it behave more like a mysql connection in that once you connect the connection stays open until the script exits or the connection is closed manually?

Thanks!