i’m in Munich and regularly ride in Austria. weather usually very good around september time.
Saalbach is also worth a look, especially if you are going b&b or self-catrering; you recieve a ticket for all the lifts during your stay if you chose the right hotel (Joker card).
Ischgl is great. some relly nice tracks and not as man-made/parky as Saalbach. area is relatively small, mind.
only ever been skiing in Schladming and it was shit. although that had more to do with the hotel and snow-cover than Schladming itself. very steep DH…!
Zillertal is nice, but there is only one bike specific trail (good, but lots of people find it a bit tricky) and the lift is rather expensive. quite a few hills around Mayrhofen are closed to bikes.
if ouy don’t mind earning your descent, look at Vinschgau, South Tyrol. not much further than Ischgl (just over the Reschen pass) and some fantastic trails. very bike friendly area and 320 days of sun a year.