I've been following the same philosophy as you are regarding upvoting comments. I've been wondering lately, though, if I should maybe forego upvoting comments and also decline rewards on my own comments. I'm wondering if I would get more engagement that way if people don't feel obligated to reward me? For those who don't reward comments much, anyway, it wouldn't make a difference, and I would hope to attract someone else who might otherwise not engage because they don't have the vote power.
The only problem is, there might be some people, like me, who want to reciprocate, or upvote my comments and might be put off by the fact I won't let them. So, I haven't done it yet, but I've been mulling it over. :)