Main problem I set-out above was caused by starting mining from the wrong directory, so system wasn't finding my modified config.ini file. Though still had constant issues with running on OS X, I found easiest solution was to run it on Ubuntu on a virtual machine using VMware Fusion. Only had one issue to diagnose, which I managed to workout myself.

One downside that probably doesn't affect anyone with 16 cores/threads or less, is that I couldn't run a full 24 cores/threads on my machine. I followed these comprehensive instructions to do this:

https://steemit.com/steemit/@cloh76/comprehensive-guide-to-mining-steem-for-both-windows-and-linux-users#@timeet/re-cloh76-comprehensive-guide-to-mining-steem-for-both-windows-and-linux-users-20160807t220847671z

The one problem I experienced (as I stated on an earlier post) was solved by hashing(#) out the last seed-note from the "config.ini" file as show below:

seed-node = 212.47.249.84:40696
seed-node = 52.4.250.181:39705
seed-node = 81.89.101.133:2001
seed-node = 192.99.4.226:2001
seed-node = 46.252.27.1:1337
#seed-node = seed.steemd.com:34191