I know what you are saying; "Power Armor? Penalties? What is this dude talking about?"
Well, for me, power armor does have some of what I would call "penalties".
1. Negates any "mods" you made to your normal armor.
Meaning if you put "Deep Pockets" on your armor to grab everything in sight...tough.
You now can only carry what the power armor allows you to.
For me this means losing 50 Units of carrying capacity.
That is a lot of "junk" I could be using to mod weapons/armor, or improve my settlements.
2. Negates any S.P.E.C.I.A.L. Bonuses from clothing/armor.
Meaning if you wear any clothing that boosts a stat...tough.
As soon as you step into your power armor, that bonus goes bye-bye.
For me this means that all my settlements lose two settlers if I wear power armor for any extended amount of time....since settler population is equal to your charisma + 10, and I have a chrisma rating of 11, and wear three charisma boosting clothing items.
So, if I have all the settlements, I lose 29 (Home Plate doesn't count.) x 3 = 87 settlers.
Since profit from stores relies upon settler population, I am losing money...and I am very greedy.
I only wish that at least "non-armor" bonuses didn't get negated by wearing power armor.
I would love to try it out on a playthrough...but, I just can't get past the penalties.