I did say I had to watch for these things, tension, etc - I am aware of this tendency. I am also aware that the practice pedal does not change key weight. What it does is dull the intensity of sound - which means that it is possible to play as 'loud' as one is able (i.e. use greater finger power) without it being a strain on the ears. Also, because it is dull, it sub-consciously encourages me to aim for greater accuracy so I hear a better sound. The dull sound is important to me because I tend to experience tiniuts and if I hear too much sound intensity, it can set my ears off for a few days. Thus, I can practice playing powerfully without suffering for it - and the practice builds the finger strength. I know poeple can argue about if that is even necessary - but in my case it has made a huge difference.
I am also aware that studies and exercises should aim at a good tone and articulation. I find it is vital to balance working with the felt and working with careful tone. If I use the felt too much than I can have a rude shock when I listen to how I actually sound. At one stage, I practiced 2 weeks with the felt (my boys were home on holidays and I was being too careful not to drive them crazy with my practice). When I stopped, my playing was awful for a few days. That was a good warning to me. I took wiht me the note learning from those days, but the articulation needed some catch-up work. The time wasn't wasted, but it was not as efficient as it could have been.
Exercises for articulation need to be with full tone. Exercises for finger power I have found benefit using the felt - I am looking for tension control / balance, finger height, movement precision, decreased effort for same outcome, etc. Maybe I have needed to practice power for dexterity, efficiency, etc because of my arthritis - but I have found this work valuable. (I am feeling and sounding old here!

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Thanks for the reminders and warnings.