@woody: I have done the same, because I bought a 70-200 4 IS second hand for half the new price in mint quality after waiting 10 years to upgrade my non-IS.
If you decide something, situation changes meaning a new lens with much better quality at the same price is available - Murphy sends greetings. But in this case it is not the case.
I was very satisfied with the strong and very consistent IQ of the 70-200 4 IS which will help me to use the full potential of EOS M, and in the future perhaps EOS M5 or a high res full frame body.
@dufflover: See above - I chose the f/4 non-IS variant of the 70-200 lenses 11 years ago and upgraded recently to the IS version for: IS, wather sealing, better flare resistance/flare patterns.
A 70-300 f/4 would be a dream lens but I am shure it will be a 2 kg lens and that leads to MY decision for the 70-200 4 IS: It is light enough to use it hours holding it in your hand. I wouldn't accept much more mass - so 70-300 L, the f/2.8 variants of 70-200 and 100-400ii aren't the right solution for ME.
On the other hand, there are 150-600mm solutions and maybe Canon will produce one at reasonable price with reasonable IQ - 70-200 for everyday-use, 150-600 when needed ...