Hi I am 30 minutes west of you (by train) in Burgenland, Austria and I would guess at "at least" a 180cm dish here - no firm details on this though I had one report of ITV from Vienna with a 180cm dish with an Invacom LNB.
I also read that reception of 2D channels in Vienna of is possible with a 120cm dish - I know people there with 120 cm dishes who are not getting 2D channels, so it has to be higher I would say.
A contact of mine in Vienna says that with his 1.8m dish, in the morning there seems to be a weak or no signal and that in the evening he is getting the horizontal transponders only.
This is pretty bad news for us all on this side of Europe so I guess the Olbort report is correct. I hope to perform some tests during July with a digibox and 1.8m dish myself but at present it is looking pretty bad under 2 metres.
Looks to me as if you should need at least a dish size of 1.8 meters in Linz. That is if about 2 to 2.4 meters are correct for Vienna. Reports of somebody (Terranus) in Munich getting 2d on a 100 cm dish and excellent LNB suggest you might try somebody's 1.5 dish and see if you succeed before you commit your money. See http://www.kingofsat.net/pl/beams.php3?s=52