It seems to me after having a good think about this and reading above opinions, that the apparently slightly dissapointing "nominal price" of 83c is irrelevant. really it only sounds like not enough due to the current oil price environment. It's not a buyout/takeover where your holding is sold for cash. You still hold stock, in a new merged entity. All that is relevant is the 1.25 for 1 ratio.
The highest SP that DLS reached in 2014 when oil was right up there was about double what it is now after the offer, or 2.5 times what it was pre-offer and BPT was a little over 2.5 times higher than current around the same time. So that seems pretty fair to me, given we're all in this on the assumption oil will get back up in the first place.
So as far as I am concerned, buying or holding 1 Beach share is as good as holding 1 share in the merged entity and 1 DLS share now is as good as 1.25 shares in the merged company, with the outside chance of a left field higher bid (well if the Brunei royal family want to buy Santos out of nowhere, who knows, bids might pop out from anywhere for anything).
I hold both LT (nominally at a loss, although originally I made a packet when DLS took my INP/ACR stake off my hands, sold high and bought back much cheaper, but not cheap enough, it kept going down...) so makes not much difference to me really who got the better deal, but just posting this for benefit of those who just hold DLS, I think you're in a strong position.