All L&L elements are among the simplest to replace. The process for changing them is the same whether they are the standard elements or Quad. As for whether or not the quad elements are worth the money I can't definitively say from experience. I personally have not seen enough of them in use for a long enough time to know from experience, however they've been in use on their crystalline kilns for several years and have achieved up to 130 firings at cone 10. That's about double what we expect from standard elements. Even if you break even over the long haul, the benefit comes in the fact that you won't be changing the elements as often. I tell my customers that if they have the money to pay for it, then go for it. In the long run at the very worst you'll come out even, but most likely you'll come out ahead.
You also have a couple of options available with quad elements. You can get the standard Easy Fire E23T-3 with the quad element upgrade, or you can get the eQuad Pro model which has the quad elements and more power. Personally, I don't think more power is generally necessary in an E23T, however if you plan to work it hard with loads of tiles or lots of cone 10 firings, then it might be worth it, in which case the quad elements will also be a good thing.
If you haven't chosen a seller yet, I'd be happy to provide you with a quote.