in my opinion all of the LP's are great, with my favourite ones being the two Dumitrescu's, the Spahlinger, Lachenmann (has some intense violent string pieces), and Bertoncini (great version of Cage's Cartridge Music).
The Finnish LP you have in mind is also very good but long sold out unfortunately.
One side of this LP was by Parick Kosk who also has a solo CD ('Mondweiß') on ERZ which comes highly recommended, this was probably my favourite release of 2009. It's a collection of his compositions with pieces from 1981 to 2008 (including the piece from the Finland LP). Really delicate and non-formulaic electroacoustic music like i have not heard it before.
Other favourite CD's from the catalogue are the already mentioned Jani Christou and Iannis Xenakis discs, and the Giacinto Scelsi CD, Jakob Ullmann's 'Voice, Book & Fire', and Gottfried Michael König. Those, to me, are all essentiell and very special.
But there are only very few Edition RZ releases i don't like. It's a very well curated label and his tastes are not far away from mine. But sometimes he gets paid to do a release.... so hands off the McGuire CD, this is really boring...
i'm not here to promote but in case you really want to buy something the best option in terms of availability and price is the tochnit aleph / rumpsti pumsti mailorder -
http://mailorder.rumpsti-pumsti.com/index.php?categoryID=268