1 new ballhead or 2?

I currently have gitzo 1541T legs to use for travel/hiking. I am planning on pairing them with a Markins Q3T ball head and RRS L plate. I also have a set of Manfrotto legs (3021 i think) with 488rc2 ball head for home use (I've travelled with it too, but man that gets heavy!).

Since I'm upgrading to an L plate, should I just transfer the Markins Q3T back and forth between the gitzos and Manfrotto? Or should I buy another (larger) ball head for the Manfrottos legs (like a Markins Q20--ideally something cheaper but still decent). Or just keep what I have and transfer back and forth between the RRS L plate and my manfrotto rc2 depending on whether I'll being traveling or not. I have a feeling once I use the L plate, I will not want to use anything else.

You could just get an RRS Lever clamp and switch it out on your Manfrotto. That's what I did for my 468 when I got my RRS L and my Acratech head. I still really like the action on the Manfrotto for my lagre tripod, and I must say it is infintaely better with the RRS clamp on it.

Keep the Manfrotto and buy an A-S clamp to put on it in place of the RC2 clamp. You could use this lever clamp, or this screw-type clamp from RRS on the 488 head (I did the first when I migrated over), or look for a cheaper screw-type clamp. Just make sure the clamp accepts the 3/8-16 threads your 488 head uses; many want to use an M6 bolt from the top of the clamp into the ballhead's neck.

Awesome, this was exactly what I was looking for! Thanks!