Where did you find it?

Given that you do not use your current 11T; swapping to the 13-34 gives you the benefit of closer ratios in the critical mid-range. But is that where you ride?

Regarding durability vs Harris's custom - no difference. Harris takes standard cassettes apart and re-assembles - labour intensive thus high cost. You can do the same to create any combination you want. Niagara and others stock Miche cogs. Miche 1st position cogs are available in 11 to 15 teeth, which in combination of inexpensive Shimano cassettes will allow you to build an incredible variety of custom 8 or 9 speed cassettes.

For one of my commuters an 8 speed 14-32 is what fit the bill: 14T Miche 1st position for Shimano 8/9 speed, Shimano 13-26 minus the 13T and 14T cogs, and a inexpensive 32T from a Shimano 11-32.