On such a draw heavy flop with how much is already in the pot after Sb donks, I'd go ahead and click it back and get stacks in ASAP. So many turn cards we're not going to love, also looks like SB has TT/77 which we can stack now.

I think that it's pretty safe to raise the flop here given the stack to pot ratio. As played, given how your average NL5 player should be relatively honest I like your line. The turn card is obviously bad and you'd really hate seeing a large bet from SB but given how he slowed down I think you're strong enough to value bet twice.

My own thinking was that SB had most likely a pair plus draw to a diamond when calling that turn, so I bet it small but I wasn't sure if I should bet bigger to target Ad/Qd. I wasn't worried about the flush coming in on the turn though after he calls, I think I'd get to hear of it pretty damned quick!

Thans guys, much appreciated as always. This deep stack stuff is tricky/scary/fun all at the same time!

The flop stack off deep means you're ALWAYS getting the money in ahead, if you flat there are a bunch of turns that you hate and aren't sure on your next move because the pot is so big. The best play is to get chips in as it reduces your chances of making a mistake on the turn or river.

Yes I think that could be the more positive way to go, thank you @harvie. It's just that not being used to such situations yet I have yet to grab 'em and do it often enough.
Learning, moving on ...