I think XCSkies is in "auto pilot" since quite a few years
Many subscribers just keep it, because even without any kind of answer, it delivers something they appreciate
As long as no serious competition appears, this might continue like this, at least until 2019 when some big changes in NWP outputs (ensemble replacing deterministic) should give work to programmers, or make it die
You can get soundings from the excellent RUC page
Anyway, I find myself dedicating more time than before to other weather pages, and just take a glance at XCskies
Windyty might have an edge if they want, they have incorporated some info from the european model to their forecasts