So I assume your only change was from a different stepper driver system (ala Xylotex, HobbyCNC, etc) to the G540 - correct? If I recall reading previous posts you are running Mach correct? Did you adjust the step timings to the proper settings? The kind of outpuit you're showing almost makes me think that if you were able to run the same speeds and feeds previously that either a) your pulse timings aren't set correctly or b) you're cables need better shielding. If you've only changed the driver then I'd investigate option A first.
If neither of those work then I'd start to question slop in the gibs or lost steps due to trying to ask too much of things - misaligned screws/nuts, incorrect/insufficient current limiting values, incorrect/insufficient voltage, etc.
HTH - take it one item at a time and make a note of how things change, it could be a combination of symptoms so if you try everything, setting it all how it was when you first started trouble shooting then go through and try different combinations. Perseverance (and a bit of luck) is the quintessential job skill
[EDIT] Rereading I see that you went for climb milling - had you done climb milling before? Climb milling will yield great results - IF you have a tight machine with no slop in the gibs/screws. You run a Taig right? I'm not familiar enough with them to give you much better insight, but since you did change processes from conventional to climb, try running it as a conventional milling operation and see how it compares. If things turn out ok then you can probably rule out the electrical issues I started off with and concentrate on mechanical. [/EDIT]