I tend to avoid icing conditions in the first place so don't claim much "experience", though I have been up to ~30mm in ~ 5 minutes on the leading edges (on a brief local flight which had an escape route into warmer air) and that was definitely the absolute limit of the aircraft.
The most I have ever picked up in normal flying was about 5mm, which on the TB20 doesn't seem to do anything.
I don't think icing conditions are usefully forecast. Stuff like icing sigmets are IMHO just ar*se covering exercises; they tell you nothing that a quick glance on the MSLP chart won't show.
This site which has been around for yonks has icing hazard charts, but I have not found the areas shown there to be valuable, over and above avoiding what is obviously nasty frontal weather on the MSLP chart.
Maybe people who routinely fly through most frontal weather find it valuable.
Same with the SigWx chart...
The worst icing I have seen (above) was in stratus cloud (NS probably), base 1500ft, tops 4000ft, in -5C which is normally the worst icing temperature in stratus cloud. I have never picked up ice below -10C in stratus, or above 0C anywhere (OAT gauges, 2x, verified accurate).
But with only prop TKS, and aerodynamic heating hardly exceeding 1C, I am not about to push it
A TBM can probably achieve about 10C of heating, at a TAS of ~300kt, and that alone almost takes you out of the potential icing band which is about 15C wide - in stratus cloud (but you shouldn't be boring along at full power in any other kind of cloud
).