from the sefer yetzirah it seems that there is both a hard and soft letter reish (see 4th perek, aryeh kaplan edition). How do you pronounce the soft reish?
In the Hebrew dialect of Habbani Jews (type of Temanim), we maintain a double pronunciation of resh, as well as a few other sounds I'm not aware of other dialects having.
The main pronunciation of resh is a regular rolled r, like exists in Arabic and Spanish. The soft resh is much like an English r, but more emphatic, as if you were about to roll it but stopped short. You can still hear this sound in some old Arabic music. The fact that this sound existed in earlier Arabic I'm sure is along the lines of more than 50% of root words in Arabic come from Hebrew - not the other way around.
Interestingly, in Habbanit our hard gimel is neither j nor g, but a kind of clicking g sound. (Soft gimel is "gh") Samekh is best described as the s sound after the k in "Mexico" (since x is truly k-s), with the tongue positioned lower than in a regular s sound. Quf is a guttural "g" sound, not as intense as the Iraqi version. Everything else is the same as normative Temani dialect.
This stuff fascinates me. ^_^