Managed to finally score a vintage pair (vintage B I believe) of RS-1's on ebay recently for a really nice price
Both the box and headphones have some cosmetic blemishes but you can't really expect ~20 year old headphones that were used to be in perfect shape (especially for the price I paid). They sound really nice and I would say on par or better than my HP1000's. The mid range is not as meaty as on the latter, but separation and soundstage is better with these RS1's. They are slightly colored which actually makes for a nice contrast to the HP1000's which are almost neutral to a fault