The stiffness numbers will give you a general idea
on the stiffness of a racket but will not accurately or reliably tell you if one frame is arm-friendlier than another. According to various posters, there are frames, other than the one you mentioned, that have an RA in the 50s and yet are very stressful to the arm. Likewise, there are frames that are close to 70 RA there are much kinder/gentler to the arm than frames with lower stifness numbers.
There is no guarantee that a racket with a flex of 60 is going to be better for your arm than one that has a flex of 68. The flex/stiffness ratings do not tell you how much frame shock
is delivered to the arm. The flex ratings do not relect the effect of shock-damping technologies
built into racquet frames.
The damping technology built into most modern Volkl (and Boris Becker) rackets is much better that most other rackets. However, it appears that the damping in the Volkl V1 Classic
is even better than the newer offerings from Volkl. Some Prince
frames worth considering:
O3 Hybrid Shark (MP)
EXO3 Tour 100 (16×18 )
EXO3 Tour 100 (18×20 )
EXO3 Rebel 98
Instead of putting a lot of stock into flex ratings, take a look at the Comfort
scores in the TW racket reviews. Generally, anything higher than 80 tends to be kind/gentle on the arm. Couple this score with feedback from users. These should provide a better indicator than flex ratings. Some decent additional info about flex/stiffness ratings in this thread (also see page 2