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, my solution is as follows: (not sure if this will help much on a Raspberry pi)

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 minor 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 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