Ok. So here's my opinion...
I think that IR is completely fine mod and it doesn't need any drawbacks because it works fine how it is now and there is no reason why to change it / nerf it. I personally think that you should also take in mind preseted guns that comes with IR3. For example Joker TAS20 - Stock which have preseted IR3 will be with that -15% fire rate completely useless in close fights, which i think shotgun should be superior in close range fights, but if this change would be implemented, all shotguns with preseted IR will be useless in close fight (which also means a lot wasted money for us, comm. for buying these guns from armas because they are now completely useless and pointless to use because any other shotgun without IR will destroy them / or SMG) and you will loose +70% of them. Which shouldn't be happening really.
Also there is a lot of guns that are based on IR (for example: Obeya CR762, OSCAR, Obir, FFA...) and this mod is that what makes the guns that they are. I mean they are very well balanced and effective now, but if you will implement the IR change, it will kill all of them because like i've said, they are based on this mod to not be useless and if these guns will obtain this slow fire rate downgrade from mod that is making them good, that will completely destroy them because they will be that slow that they will be no longer good for any range fight. Maybe only for Sniper range fights which is 65+ meters because you want to add extra +ranges for exchange of fire rate so that mean that they will be nearly effective (DMR's ok) as snipers because of that +very big range that they gonna deal full damage at.
I think that IR shouldn't be touched because its completely fine mode that have its use and potential. I personally would keep the mod as it is now because its also gonna have big impact on AR's. With IR3 on AR's you will be with +12m effective range able to completely destroy not only Rifles but also Snipers because AR's (N-tec, and its reskins / etc.) are all ready very good gun's overall and they will with this change gain a big buff that will effect gameplay massively and im not worried to say, completely destroy weapon balance.
Right now your doing very good job of fixing / buffing / nerfing guns that actually are broken / op or under-looked (because of their weak stats) but i really don't think that we have asked for this IR change and its really, really not needed. And if this is all because of shotguns ranges that they are able to 2-shot at big ranges than just tweak a shotguns a bit, but not the whole mode which will effect whole gameplay and nearly every gun in the game.
Thanks for reading this, and i hope that there are people who agree with me and this opinion will lead to something...
Regard's Boowy / Kazui.
Thanks for attention.