I think what is so interesting about the event and the world record is beginning to really understand how fine the line is and how little margin for error there is when trying to run the perfect race. And I know this exists in all events but the 800m just seems different because there is an element of pace management involved but at the same time it's pace management at basically the anaerobic threshold limit which means any portion of the race (even say 150m of it) run inefficiently massively compromises you.
The concept of pacemaking in the 800m is an interesting one - especially when you start getting into sub 1.42 running. We roughly understand the benefits of pacemaking right - a energy saving due to some form of drafting and some kind of mental effect of being able to "watch a shoulder" for some portion of a race - though obviously in the 800m, being the shortest distance that has pacemakers, the question is how much is that benefit worth? Especially going back to my earlier point about how fine that line is with pace judgement and you start to understand that a pacemaker would basically have to be able to run 5-600m at splits perfectly tailored to the athletes physiology in order to really see what guys can run.
The best case in point is Kipketer in 97 - 1.41.24 in Zurich at an evening meet with absolutely perfect conditions, except the pacemaking - while impressive - was actually bad, with Tengelei splitting around 23.5 at 200m and 48.10 at the bell with Kipketer right on him (so maybe 48.3ht). 11 days laters at an afternoon meet in Koln with some breeze in the stadium, Kiptoo hits 49.00 with Kipketer right on him (maybe 49.2ht) and of course runs marginally faster than he did in Zurich. There is no doubt the pacing cost him there - had the splits been 48.6 for Tangui and 48.8 for Kipketer it's very plausible the WR could have been in the 1.40.8X range before Rudisha even laced up his first pair of spikes.
Rudisha in London is the interesting one for me - no he didn't have a pacemaker but he had a number of things in his favor. 1) Incentive/Motivation - the Olympic final which there of course is no greater incentive or motivation in the sport. 2) Perfect conditions - as close to no wind as possible and an optimum temperature (around 20 degrees celsius) and 3) Rudisha was able to completely dictate the pace and run it exactly as he wanted to. There was not a segment of the race he didn't control or feel "obliged" to alter based on someone running in front of him. No 200m split is stupid - 24.3 at 200m, 49.28 at the bell (24.9), 1.14.30 at 600m (25.0) and 26.5 to close.
So of course it's interesting. Put a pacemaker in London and there is a benefit for Rudisha of some drafting for maybe 500m but on a still night this is minimized. Possibly a mental/focus benefit but with an Olympic title on the line this is also minimized. On the flip side he can judge his pace perfectly and never has to temper or cut his stride worrying about clipping someone in front.
I honestly believe that in these upper human limit 800m races (under 1.42) the race is so short the net benefit is greater without a pacemaker than with. For the the net benefit to be greater with a pacemaker they would have to in essence almost be a clone of the athlete and so incredibly in tune with the pace, down to half second increments per 200m. I just don't think that's possible or plausible.
I think Coe without Konchellah in his way in Firenze runs 1.41.3X. I think Kipketer without Tengelei in Zurich runs 1.40.8X. I think (and this is no respect to Rudisha he's the greatest ever) Rudishas WR from London is not bettered with a pacemaker (seriously go watch some races with his "preferred" pacemaker just running idiotic 450m "jobs" where he gets out 6-7m ahead of Rudisha and actually slows down so Rudisha can get to him before dropping out - that's not pacemaking).
The one thing I would disagree with you here on is that as much as I love Ovett (my favorite miler ever), there is simply no way he would ever sniff running under 1.42 - he just wasn't that athlete. I think he could have run 3.28.8 at his prime - but not in the 41's :)