Can someone speak in everyday terms about...
Can someone speak in everyday terms about the difference between this and the TPS 520? I've seen plenty of citations of the difference in soles, and then a description of the materials of those soles right off the product page. But can someone explain the difference in how they feel? Is one better suited to backpacking with a load vs one more geared toward lighter hiking or something?
I'm looking for boots for backpacking, and they'll be replacing my TPS 535's (same as the 520 but they're just leather, no gore-tex). Never had a problem with water proofing on those.
In addition to how the sole feels, is there a difference in breathability between this and the TPS 520?
The TPS 520 is going to be a heavier boot with less technology advances - simply put. Both would be good for backpacking - and it depends more on preference than it does load to a large degree. Both are heavy backpacking boots. The 520, along with it's weight, has a slightly deeper lugged sole.
Old school thought is that backpacks have to be heavy and you need a heavy boot for support - been down that road. I can speak from experience I like to carry no more than a 45 lb pack and even over the roughest terrain for longer distances, I like a boot that weights less - every step you have to take expends less energy with a boot / gear that weights less - light is right. That said, some people still prefer a traditional boot (I have a pair of 520's - they are bomber) and some people prefer a boot that incorporates more technology ie: the 535 (they are going to provide support with a little less weight and have a slightly different feel).
If I were to make a recommendation, if you don't already know why you WANT the 520's, go with the 200's.