The YJM100, as I'm sure you know, is old-skool Plexi and would be good for the DP band. But if you're happy with the AFD100 then I'm not sure it's worth buying. Unless you just want to buy another amp for the fun of it of course!
If you're after flexibility, what about a Bogner XTC? They have the "Plexi" mode you could use with the DP band, and super flexibility for your rock covers band? The 20th Anniversary version is supposed to be superb, if pricey.
I have an XTC Classic and wouldn't swap it for anything - it's an incredible amp.