I never noticed much of a difference-I just like the taste of strong coffee.
I’m not a coffee drinker, but I’ve heard horror stories of people being served caffeinated coffee at restaurants while asking for (and being told that it was) decaf. So I can imagine a decent unleaded being quite acceptable.
To the OP, any chance other beverages might scratch the “need a hot beverage” itch? Tea? (there are some that are lower caffeine, and I think almost any tea has less caffeine than coffee).
There’s an overlap in flavor. Most decafs are kinda shitty coffee, but there’s a lot of regular coffee that’s shitty, too. And the best decafs taste nearly like the real thing. But the “Cometeer” I’ve been drinking is good enough that i looked up it’s caffeine level (not that i remember it now… but it was pretty low) because i was surprised by how good it was.
I’m going to try the stuff @Aspenglow recommends, though.
When I used to attend meetings a my synagogue, there would always be the brown-rimmed pot and the orange-rimmed pot on the dual Bunn hotplate. But someone on the office staff told me both pots were always decaf. 
Amen to that. It’s hard to find palatable coffee in a regular diner/restaurant. One of the reliable good features of life here at The Home is that the coffee is always excellent.
FYI, my current fave at home is Stumptown Roasters “Hair Bender” (whole bean). With a name like that, you’d expect it to be really strong. But it’s a medium roast that (to me) tastes the way coffe is supposed to taste.
You might want ti try drinking chicory, then. The taste/color/aroma are closer to coffee than any tea I’ve ever had.
Remember when people used to drink Sanka?
So we do a caffine free fast every January (sorry to break it to you, but its also booze-free,vegan, and carb-free. But the caffine free bit is only bit I find difficult 
)
I’d second the chicory coffee idea. That’s our go-to caffine-free coffee substitute (you can get it freeze dried and its pretty tasty)
Another one is date seed coffee: Date Seed Coffee (Caffeine-Free Coffee Alternative) - Alphafoodie
I admire your resolve and am writing to wish you and your mother well. I am not the most experienced decaf drinker, though, having tried little but the bottle of Taster’s Choice I keep around for nights and after shift work and attractively priced from $4 when on sale, which is often.
If your mother was advised to give up caffeine it is noble you are trying to support her efforts. As far as I am concerned, if this doesn’t work after a reasonable try you are permitted to resume caffeine. It may or may not be causing the hypertension, which has many causes.
As an unrelated question, is there a good source of unroasted green coffee beans?
You have probably done the Googlework^ already, but if not, here is what SpruceEats suggests:
^GoogleWork is not the same as personal recommendations; everyone understands this.
I switched form coffee to tea a year ago, which led to my gf going to 50:50. She uses equal amounts of real coffee and decaf. She is very happy with the taste and efect.