Well someone here solve the last ckpool solo block using 10TH worth of Apollos Probably why the pool has attracted more Apollo users since then.
The benefit is that you are using your own node to construct and broadcast the bitcoin block if found, with ckpool, the pool itself has control over the block creation (and therefor could theoretically censor transactions). Until we release our own implimination of solo mining I would not suggest trying to do this on your own unless you know your node is well connected to other pools (which is hard to do on an individual level). We are working with pool partners to directly connect all Apollo solo miners to major pools once our implementation launches.
You mentioned in theory ckpool can censor transactions, wouldn't exactly the same statement apply to the "Apollo Pool" since you said the plan is to connect to other servers?
At the end of the day using any pool you need to trust the person behind it.
GBT 'allowed' it, but over the many years GBT existed, no one ever wrote anything to do it,
not even Luke who used to spout this as a reason to use GBT.