TL/DR, scroll to the bottom for my answer to the specific question of the topic.
S&W has fantastic designs and the newer two-piece barrel design is certainly an improvement from the traditional barrel.
The quality of parts is, well, DIFFERENT. The newer MIM parts are all built to stricter tolerances that all play well together right out of the box without any help from a craftsman — which is good as S&W has no craftsmen building guns.
However any/every S&W revolver made in the era of MIM feels different to me and I don’t care for the DA trigger stroke.
Revolvers are built by low wage assemblers. S&W also has quite possibly the absolute rock bottom worst QC in the history of their brand.
Yes, it is true that in the age of the internet, everyone gets to hear about every single problem, but if you were to hang out on the S&W Forum, you would see the endless laundry list of completely ridiculous problems they ship.
I would not recommend a new production S&W revolver to anyone today. That’s not to say you cannot get a decent one, they certainly exist. And yes, you can find old (original) issues with older S&W revolvers too.
If you hang around the brand and their life long fans, you may get the feeling that much of this is generational. Guys who love guns from the 1930’s to the 1950’s will scoff at the shoddy S&W revolvers from the 1970’s and 80’s. I certainly understand that, but the quality control today is an absolute tragedy.
The shining light, at least in my opinion is that the DESIGNS are still legendary. If you can carefully inspect an example and you also have the patience to deal with customers service and warranty work, you can come up with a great gun.
You asked a version of, “do the post ILS revolvers match the quality of the pre-lock revolvers?”
My answer is no, they do not, for dead sure certain. The QC is the problem, not the design. And specifically to your question, the ONLY difference right now is that the hole is not drilled in the frame and the silly lock unit is not present. But the hammer is still MIM and molded for the lock.
They do not make sweeping changes to all the parts and the guns with no locks are just a part of the revolver lineup, most of them still have the lock.