Thanks for that - I've been checking every day on both MAV and OEBB and finally today I can book on MAV - great prices too, especially for 1st class. I guess OEBB will follow tomorrow but, yes, it's sure to be more pricey.
If I go ahead and book 1st class on MAV do you know if I'll be able to choose carriage / seat?

Also: I'm sure in the past on OEBB I've been able to choose seat/carriage prior to payment when booking but now when I do a dummy booking there doesn't seem to be an option for seat selection (even with reserved seating in business or first) - does the seat selection option come up after payment (on OEBB)?