I haven't hit a ball in WGT since end of June last year, but when I first started, back in 2010, I was a ding putter, because i didn't know any different. It was probably some time within that first year someone I used to play regularly with - Borlick - told me about off-ding putting. Tried it... and never looked back. I have always found it far more forgiving than moving the marker and trying to ding.
Just like AnaNikolaj, up until last year (or maybe the year before) I stuck with the same putter - Daytona Rossa - for the same reason... didn't know how precision/forgiveness would affect off-ding putting. Plus, the Daytona was one of the best putters at the time.
In more recent years I found with the Daytona putter that the ball sometimes wouldn't start anywhere near where i thought it would. For example, for a right to left break, I would move the aimer to the right of the hole, and hit late, and yet the ball would still start straight at the hole, and so miss the hole because of the break. I figured that must be down to foregiveness/precision (maybe the specs had changed/diminished over the years?) so I tried a putter with better precision, and bought the one I have in my bag now, and it is definitely more accurate.
With regards how I work out how much I need to miss the ding by and whether I need to move the aimer, there are no calculations, it's just trial and error, experience, and (as with real putting) feel. Back in the days of Flash I rarely moved the aimer, but since we lost Flash I found that you have to miss the ding by so much more that it became almost impossibe for many putts, so now I move the aimer on 80% of putts, sometimes maybe just a fraction, as well as missing the ding. I have found that moving the aimer even a small amount helps with foregiveness.
Jure - I found the L98 Scotty Cameron putter to work really well with off-ding putting, particularly with precision, i.e. the ball starting on the intended line rather than forgiveness taking over and missing the required line of the putt. Also, I picked the M1 model as it resembled the meters of the Daytona, so I didn't get caught out with playing different meters to what I was used to.
Dneirf - for someone who puts all that effort into calculations, your putting stats are very poor to say the least; only 30% one-putts and 18% three-putts wouldn't give me any confidence of your methods!