Your message concerns me. The bottom of the range is especially troubling -- CoaguChek XS sometimes reports values that are slightly higher than blood draws (there are numerous reports about this - and my past testing also demonstrates this). It's no problem if your values are above, say, 2.4 or so, but it is possible that a 2.0 on the meter may be 1.8 in a blood draw - a worrisome number. You should go for a minimum that is no higher than 2.5, in order to fully protect yourself.I do labs because of I cannot do home checks without a machine. They use Coagcheck at the lab I go to. We have the INR at 2.0 to 3.0. I have a aortic St. Jude's' leaflet and got in 2001. I feel safe they way we keep my INR. It is affected by activity and antibiotics. I never read stuff online from unreliable sources. Like you, I like safe numbers that makes sense.
You shouldn't feel safe if they keep your INR between 2.0 and 2.5. That's below clinical recommendations and some people (including me) would consider this to be taking an unnecessary risk.
You may be able to convince your lab to try to keep your range ABOVE 2.5.
If possible, you should have your clinic test your INR weekly. Those who test weekly are shown to stayin range much more consistently than people who test less often.