Like many thing it depends on YOUR requirements.
Example1, I shoot APS-C with a 70-200/4 rather than the f/2.8 lens. For primarily daytime shooting, the f/4 lens did just fine. So if you are primarily a daytime shooter, the 40-150/4 should do you fine.
Example2. I was shooting a graduation event with the 40-150/2.8. And I was glad that I brought that lens. They turned off the lights
I told them "no light, no pictures." I got the ASB advisor to turn on ONE set of lights. I was pushing the exposure down at 1/60 sec and sometimes slower. I had to cull out a bunch of subject motion blurred shots. With a f/4 lens, I would be down at 1/30 sec.
Old saying, in LOW light, fast glass wins.
Example3. For travel, at my age, I am weight sensitive. 1 pound more may not seem like much, but when lugging the gear EVERY DAY, NON-STOP (no rest day in the middle), it gets tiring. It is no fun when you are so worn out by lugging a heavy kit, that you don't want to lift the camera to take a pic. That is why I switched from APS-C to m43.
If you are weight sensitive, then the lighter 40-150/4 would be the better choice.