Both the 520 and the LHT are designed with full blown unsupported touring in mind, not that they can't handle smaller loads as well. If you ever see that in your future, both are excellent bikes but if lighter bike packing touring is more what you see now and in your near future then yes, they are likely overkill. I would then consider the Diverge and other similar bikes including cyclecross bikes that have brazeons for at least a rear rack (which comes in real handy even when going light)