The R is more forgiving. It is 460cc and has a slightly shallower face that is longer from heel to toe. This gives it a 35% bigger sweet spot according to Titleist. I just got one and have only played it once. I had good results for the first time out, it was longer than my Ping G2. A lot of that had to do with the shaft. I went from an Aldila NV 65S to a Grafalloy Pro Launch 65R, the Pro Launch has a lot more kick.
Get on a launch monitor and test different head/shaft combinations. That's the best way to find which works best for you.
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