Alright, I'm going to officially declare myself the "pacemaker expert" of the forum. (If anyone wants to defute this, go right ahead) I got my first pacemaker when I was 7 years old. Now, 20 years later, I am on my 4th unit (but original wires!).
When I was young I was not allowed to go through metal detectors at the airport. I was told it would "reprogram" my pacemaker, which really freaked me out (I am 99.9% dependant on my pacer). So I have many embarassing stories of being frisked in the airport. Oh, well. However, after I got my third pacemaker my cardioligist told me it was now okay to go through metal detectors, as the device is more protected now (or something like that). Well, I've been through many detectors since then. However, with the new 9/11 alerts, it is possible they have cranked up the magnatism on the metal detectors, and therefore it would be a problem to go through them again (I haven't been to an airport since 9/11. Just don't travel much). But I was also told that while it does "reprogram" it, that only lasts while you are actually under the magnet. It would act just like when they put the magnet over your pacer in the interrigation. As soon as you take the magnet away, your pacer will go back to normal. So do not get too freaked out by things like that...
As for feeling it... Some people notice their pacers working, but I only do when I hit my top limit. That used to happen a lot more often until they upped my limit to 160 (or something like that). When it was 120, I would hit it all the time, then feel lousy. But no problems now. I never notice it increasing my hr, as it has to do that all the time anyway (ventricals use it 98%).
The great thing is that you can have confidence that your heart rate won't drop dangerously low. But it doesn't always stop arrythmias. It just depends on how yours is programmed. I've had my unit reprogrammed many times due to various arrythmias. But it's nice to know that is an option!
Anyway, I'll stop for now. If you have a question, just let me know.