You may want more power, depending upon your room and listening habits.
I bought and rebuilt the tweeters on a pair of MG-1 a couple years ago using a factory-supplied kit. Be aware that there are a couple incarnations of these (MG-1, MG-1 improved, MG-1a, 1b, 1c before they went to the 1.# designations...
http://www.integracoustics.com/MUG/MUG/articles/speakers.html).
As Steve pointed out, make sure you check for buzzing which may indicate wire delamination or, worse, a tear in the mylar.
The other issue is the tweeter wire on those early maggies were aluminum and prone to oxidation. They can basically dissolve away anyplace the wire is exposed to the air, which was the case on the pair I purchased (I knew at the time, but got such a deal that it was worth buying and repairing). This of course causes a break in the signal and your two-way maggies just became single-driver speakers. Check to make sure there is sound coming from the tweets, though that's no guarantee they'll continue to make sound.
Repair of the tweeter wire wasn't difficult, though I don't think I would want to tackle the bass wires. Here's a link to some photos of my rebuild. I also took the opportunity to replace the original caps which were nowhere near matching eachother.
http://s896.photobucket.com/albums/ac170/AudioSnoop/Magnepans/Magnepan%20MG1%20Rebuild/Haven't been to PhotoBucket in a while... seems they've lost all my descriptions of the rebuild.
