I appreciate the answer. So there is no reason on why I shouldn't use this new service after I move my bitcoins somewhere safe?
Well, as with most service, there are obvious risks associated with it. As a rule of thumb, your private keys should never be shared with anyone else. If someone happens to send coins to that address or if your identity is tied to that address, your coins could hypothetically be stolen. Especially with seed, you have to consider those addresses compromised once you've exposed it. If you do import your seed there, remember to send the coins to another address not associated with that seed first.I'm not saying that they aren't un-trustworthy because I haven't tried them myself. I would rather personally spend more effort to just do everything by myself instead of entrusting it to a third party.