Canon extender 1.4

I have the original 1.4 V1 extender and Im thinking of upgrading to the V3 but can't find any information on the differences.
Is there a big enough difference or should I just stick with what I have.
Im currently shooting with the 7D markll and thinking about getting the 100-400 ll.

All three Canon 1.4x teleconverters have similar optics. The 1.4x II added weather sealing and some new coatings. The Mk III has updated optics and new Flourine coating. I would only upgrade to a II or III if you have lots of money as most people don't see a noticeable difference in image quality.

More info here: https://photography-on-the.net/forum/showthre​ad.php?t=41922

After having used the I's and II's for quite a few years, I immediately noticed improvements in CA control and other subtleties with the III's. To me the differences are desirable enough to upgrade, but how particular you are, the bodies/lenses you use, the subjects you shoot and under what conditions are the determining factors as to whether to upgrade or not.

exactly what I was looking for, thank you so much!

The Mark III versions are also said to have CPU capacity to make them a better match for newer lenses, like the EF 300 mm f/2.8L IS II USM and similar. Thius that should guarantee the best AF performance from these lenses, when combined with a converter.

But I don't know if you'll notice the difference. I don't have any older converter than the Mark III versions, so I can't compare.