I am not a fan of any piercing in children, unless it is a cultural thing (eg tribal/very old tradition) - and I am heavily pierced myself.
If you want to do it, go ahead, as they are your children and they are too young to make the decision for themselves at the moment....but please get it done at a reputable piercer with a needle. The ear lobe is just skin, so it won't hurt much. I think most of the reason why guns hurt is that the blunt end of the stud is being forced through at great speed, with a lot of pressure. It's like getting a piercing where a clamp is used (navel/tongue) and most people end up with more pain, bruising and swelling from the clamp than from the actual needle. I can vouch for this...clamps hurt! Not on bits like ear lobes though, becuase it's stretchy skin.
I had my lobes done when I was 10, at a chemist with a gun, and I have had endless problems with them UNLESS I wear sleepers (which of course you cannot do right away with a gun piercing). If I even so much as put studs in for a day, they get infected.
It's totally up to you. Personally though, if I was in your position and my DH didn't like the idea, I would wait.

