You may only want Brian's input on what you actually need, but I know Cameron's are 4 degrees standard loft. My old Yes Callie came standard with 2 degrees of loft. I emailed Yes about the small amount of loft in their putters and they told me that the grooves in their putters work better with a little less loft.
I do know that how much loft you need has a lot to do with your hand position at impact. Utley uses a forward press and wants the hands leading the putter through impact, so he needs more loft. You may or may not need as much as Utley. Plus, the greens you usually play on may effect how much putter loft works best for you. If you putt on slower greens you might putt better with a little more loft. Plus, a Yes, or Rife, or other grooved putter might make a difference in what loft works best.
For me personally (and this is ONLY me) my Scotty is at 5 degrees loft, 69 degrees of lie, and is 35.5 inches long. My swing weight is D-5 with a total putter weight of 500gms. My hands are a little forward at set-up and my hands lead the putter head to impact. Here in West Texas, 95% of our greens are bentgrass.
I apologize if you only wanted Brian to respond