I have a set of the Pomona 6275 probes too, and have encountered the exact same problem with wire fatigue right at the strain relief.
I cut back the strain relief, cut out the break, and resoldered the ends with flexible heat-shrink to form a new strain relief with a more gradual curve. I'm sure it will happen again at some point, but this has been holding for about 5 years now.
I bought a second set as a backup in case I'm in the middle of something and don't want to stop to deal with probe issues.
The ProbeMasters look ok, but the grip area seems too far from the tip. It's not like I need all that distance when probing low voltage. I think I'd rather have better positioning precision.