Equipped my commuter/touring bike with a full set (2+2) of V-Brake version some 2 years ago. The headlights are not sufficient to ride through a forest, but for commuting they are fine, and no complaint about rear lights.
They worked pretty reliably summer and winter, but I had some failures:
The first versions had the light-Module attached to the generator/brakeshoe with a weak press-on connection. Since the LED modules are exposed, they have come off (simply disappeared) three times so far, with the connecting wires ruptured. Fortunately one can order spare modules (soldering work), and now glued them with Loctite in addition. Another unit failed after the generator had contact with the rim a number of days. There is a PU patch to protect, but it quickly wore off.
A general trouble is when changing the brake shoes of the rear units (at least V-brake version). This requires the generator unit be displaced from the brake shoe unit (tiny allen key required, too small to be part of typical bike multi-tools).
Do not forget to check the PU patch and replace, when worn.