Also I don't want to argue against your point that Farah has showed greater "range in short period of time" then Aouita, I just want to put your points little bit in the right context.
Farah's range is very impressive, no doubt.
But just a few facts ragarding Aouita:
He has achieved his times over a quarter of a century back.
The times you have listed from 1986 and 1988 don't reflect his abilities in these seasons at all.
His Mile win from Berlin '86 was not a race for fast time. He wanted to prove that even in a season where he concentrates more on the longer events, he still can beat most of the top milers in their speciality. He definitely was capable of running faster, also not close to his best from '85.
In his 10000m from Oslo he also just wanted to prove that he can beat the specialists (first to list here Alberto Cova) also over 10k. Cova before has declared the 10000m to be "his" event. The world record over the distance was planed for 1987. In Olso - in his first attempt over the distance - he ran big parts in 2nd land, easly worth at least 10seconds.
In Nice 1988 he just ran a wonderful last lap, no intention also here to run some record time. He just wanted to get into form for the very late Olympics in Seoul. In August Aouita concentrated more to get a sub 1:44 over 800m. I don't know how fast he could have ran in '88 over 1500m, but definitely faster then 3:32.69.
Aouita's range is better reflected by the fact of winning against some of the best over 800m, then against all of the best in the world over 10000m, and then again against most of the best over 800m. That's absolutely unique.
But was Farah has done also is unique, maybe better, I don't want to value this. But in a different manner.