He's probably a little less loyal than the other two guys, who've been traded a grand total of once between them (and KG had a lot of say in that one deal), but that's probably because he's experienced the business end of the game more.
I think Allen fits in fine as a starter and 3rd or 4th option in a Rondo-led, fast paced offense. If the offense continues to be designed around Pierce (not saying that's a bad thing), then you might as well get Josh Smith, who loves to play just as slow as 34 does.