Bought mine a month or so ago. No mods other than Yonex overgrip. I'm running Lux Alu at 55 in the mains and Babolat n.vy at 57 in the crosses. While arm comfort wasn't the primary concern for me, this racquet has allowed me to run the poly/syn gut hybrid a little tighter than on other racquets with far less shock. Since I live at altitude, the tighter setup has given me more ability to keep balls short of the baseline.
I actually just played a few days ago at the clay courts in Frick Park, Pittsburgh. That was my first time playing at somewhat close to sea level in years, and the difference is not minor. I only mention this because I felt like the ki5 had a ton of spin potential and was great at whipping around for sharp angles; yet I was also able to hit through the court when necessary. It felt almost tough to hit too long, but I didn't leave many short balls either. If I was playing here full time, I might consider dropping the string tension a pound or two.