The description of the diversion is incorrect: the A702 is not closed at Hillend, and the closure at Flotterstone and the suggested diversion via Seafield Moor Road is very poorly signed: heading to Carlops this morning, blithely unaware of the disruption, I saw one single yellow sign, right next to the turnoff on to Seafield Moor Road i.e. a bit late in the day. A bit more advanced warning would have been helpful: AFAIR there was nothing else between the Lothianburn junction and that junction to prepare road users for the diversion. As it was, I turned off just past Boghall Farm (where there was a clear "road closed ahead" sign) and went past the Technopole and the science park to the Gowkley Moss roundabout, then down through Auchendinny and along the B7026 to Leadburn, then the A701 to Lamancha where I snuck across to Carlops via Macbiehill. The return journey was the same in reverse (no way would I ever try to head back to Edinburgh along the A703 and that horrible junction at Hillend unless they had actually closed the A702 there - as it was, a steaming great lorry pulled out in front of me and the car in front as we came round the bend doing no more than 25mph).
Unlikely to improve things wanting a quiet cycle in non-A702 bits of Midlothian.
I can confirm that on the way back there was a lot more traffic than I would usually expect to find on the A701/B7026 at 3pm of a Friday. The Leadburn junction was a mess with tailbacks in all four directions - it couldn't handle that volume of traffic wanting to cross the Peebles road. (And, if that was the start of the evening peak then, well I know Friday is POETS day but heading home at three o'clock is taking the mick a bit, isn't it?)