I disagree. I think it would have been at the absolute apex of his ability and I don't see him smashing that mark, but we have plenty of pertinent things to suggest (at least in my opinion, doesn't have to match yours) he could have been a second quicker and that obviously puts him right at the cusp of running a 3.24.xx
We saw him run 3.26.96 in 2002 off 2.44.75 and this was right at the end of his peak window in the 1500 and probably even just a little past it (1998-2001 was for me his absolute peak).
In the 2001 Van Damme meet he led Lagat through 1200 in 2.46.10 and ran 40.02 to run history's second faster time but this was with (by todays standards and what we now know about the benefits of truly even pace running), horrendous pacing - a 54.0 followed by 56.5 and then ramping back down to a 55.6 for the 3rd lap. When you look at how the WR was run (I know some people dispute the final 300 of 39.66 but all we have to go off is for certain a 2.46.34 at 1200), I feel like had he been able to split something like 54.8, 55.0, 55.1 in 98/99 he could have run a similar last 300m to that Brussels race and with wavelight he could have been that pinpoint because we have seen exactly that from Jakob in all of his record races.
With regards to spikes? At his level of ability - form, efficiency, supremely trained, peaked etc, I mean it's a "more cushioning vs slightly less force into the track" equation and over 1500m I would doubt you are seeing any great difference. He's not some college kid with sloppy form who is super eager to destroy himself in track workouts where those products would really help him. His scope for improvement here is also pretty tight considering he's operating at the absolute pinnacle of humankind for this distance already.