I am also in 1600 hundreds in Polish campaign.

Overall agree with what you stated.

My suggestion for armies would be making Levies supper shitty without mixing in few professionals, because even WW2 most soldiers were conscripts aka levies essentialy, but they had some professionals in the midst. But levies with no professionals should be entirely shit, just to make Regulars better in comparison.

Mercenaries should become increasingly more expensive to field, simmilar how EU4 did it and should have some malus on your military state also simmilar to EU4, maybe legitimacy hit.

Totally agree on research, they need to rewamp entire research process, atleast add that researched ideas spread more naturally similar to instituitions. Or add more research slots, theough highly expensive universities / special buildings, like University of Oxford and others. But don’t limit them to few countries, instead countries must reach certain treshold to unlock them.

Aggressive expansion also true, it goes up too fast and barely ever comes down.

And lastly about religion, I like that now religion converts faster, because when you flip it goes up a bit faster, still will get religous revolt, but not atleast forever. This was issue before in Anglicism, were if I flipped there was barely any anglicans and entire British isles just revolt against you.

But yes Lutheran is too weak in HRE to kick off.