I'm going to stick my neck out a little here, and vote Yes.
I've seen Paragon classes in play before. I think they add an interesting multiclass option, one that can be used to butress various PC builds.
Orsal's point is a good one. I don't know that I want to see a 23 str half orc any time soon. But considering we had a 1st level orc PC w/a 22 strength, we've already kind of let that cat out of the bag. There's a price to pay for that sort of specialization. I've also taken a step back on my concerns on balance. Parties in LEW are rarely all of the same level. Widely disapate power levels are often seen w/in the same party. A paragon focus on one ability score might just fit right in. In a sense, that's an advantage of the persistant world. Your PC won't have the same companions his whole career. I feel there is less stress on players to create an iconic type of PC to fill a needed roll in a party. Since parties are constantly changing, the player is more free to create the PC of his choice, w/o excessive concern for party balance.