They may experience electrical impulses but I believe it ends there. It's a stretch even to say they "feel" them. Without a brain to interpret them it is simply an impulse and a reaction from the plant. There is nothing to convert the impulse into emotion or feeling as you said. Certainly not the way the human brain can do so. Anyways, like you said you'll argue till the cows come home and I'm in no mood to do so.
To stay on topic. No, I would never steal plants without permission. Not just because of property rights, which I completely agree with. But because of things that happen like the link Warren provided. There's a lot of nutty people out there and they don't all stop to ask questions before pulling the trigger. Besides, like katya said, the golden rule. I wouldn't want some crazy plant fanatic running around on my newly purchased property digging holes if I didn't know what was going on. If they're choosing to clear the lot they probably won't be object to someone taking something beforehand.