In a way, I wouldn't mind a year...if I felt sure of a site and the fact that it wouldn't be hacked. My strategy is more long-term and less daily play.
BTW as a follow up to my experiment, the transaction still has not posted to Coinbase. I haven't checked Startminer for any updates as per yet.
Re:
Coinbase changing the deposit address is completely normal. It should not cause any problems whatsoever.
When I press 'deposit' on my Coinbase account, I get this message:
Only send Bitcoin (BTC) to this address: Sending any other digital asset, including Bitcoin Cash and USDT, will result in permanent loss.
I had forgotten about that exact message but it caused my concern about the address changes. I'm still not entirely sure which message to believe regarding m Coinbase wallet.