Balance is definitely going in the right direction in my experience.
The thing that is hurting the IS is two fold:
Some of their equipment is pointlessly nerfed and thus they are shooting themselves in the foot, got nothing to do with the clans.
The bigger operational problem, the stuff that gets me killed and loses rounds, is the same thing i am ALWAYS harping on, that is, lulvariants.
Horrible variants completely cripple the IS late game, the Atlas has horrid variants, the Mauler doesn't have any good medium killer variant, its ok vs heavies and lights but mediums and assaults it has trouble with, the only thing left most of the time is the Awesome, which does not have the armor or podspace to fill the role it is asked to fill. The Atlas C is only good in certain situations, but its being forced to pick up the slack of the other variants and its weaknesses are showing.
Now, the clans have lulvariants too (I'm looking at you Gauss Loki, even Uller Prime tbh) but they're less noticable because clan tech is just better and can make up for it easier.
The only MECH itself that is in bad shape is the Hollander, its really hard to find a place for it in my line up. Everything else can be brutally effective if equiped correctly. See Thanatos C compared to Thanatos Prime as an example, its uphill to do any real damage with the prime, but the C can solo a novacat if you're sneaky.
The other day I was doing really well early round on sandblasted and decided to rush an Atlas prime, I ended up killing one medium and dieing by a small gang even though I had support, I felt completely useless. Next spawn I came back as a Warhammer prime and mopped the floor with the same players in the same mechs with less support, the Warhammer is doing its job, the Atlas is not.
By the way, I have thought about the Hollander and I feel that all its variants have a decent role except the Prime, the price needs to be brought down to CDT level to make it worth taking in my opinion.