Isn't that rose Mercedes from Geschwind considered as extinct by Erich Unmuth and Andrea Buchmann. That's what I read in Das Rosenjahrbuch 2011. And is written in the description of Geschwind's Mercedes on HMF:
"According to Erich Unmuth, it is questionable whether 'Mercedes' in gardens and in commerce is the original Geschwind rose - see References."
And in one of the references: "(from: Möller’s Deutsche Gärtner-Zeitung 1886, p. 66-67)
…Rud. Geschwind sent us last autumn 13 different climbers under the name „Hungarian Climbers“ to bring into commerce and thus have them tested by roselovers…
Mercedes: Variety of de la Grifferaie, with a similar habit and foliage. Medium size blooms, flat cup form, flesh-pink-lilac, very floriferous, in many clusters, hardy."

This is the plant received from Zvolen as a Guillot Rugosa Mercedes. I received another one Mercedes also from Zvolen as a Multiflora Hybrid. Is there any place where the "real" Mercedes by Guillot can be found ?