We had Skylights Unlimited install a Velux Solar Powered Opening in our new home in 2014. In general the actual Velux skylight has been excellent - I like the solar-powered opening ability, and the auto-close when any rain is detected. We have had Velux come in to repair the unit - steam from a shower below rusted the battery connections in the skylight itself, but this is likely more of an issue with the bathroom fan installation rather than the skylight itself.
The real issue is with the join between the roof and the skylight. We're re-insulating the attic now (2020) and have noticed extensive water damage at this join - i.e. years of slow leakage at this join. Clearly this was not installed/sealed properly in an area where most customers would not see the issue for years.
Velux is a good product, but its also critical to get a good installer - Skylights Unlimited was not a good installer 6 years ago, hopefully they're better now...
Dec 10 Update:
I've been talking with Skylights Unlimited about this issue and they shared the attached photo that was taken after the installation in 2014. Given that there is light getting into the attic along the join between the skylight curb and the roof, they strongly believe that the problem was with the original curb installation, and not their curb extension that they installed. Once I have a roofer get up there to fix the issue and take more photos, I'll provide a further update on this.
Regardless, Skylights Unlimited has been very professional about communicating with us on this issue.
Rating bumped due to how they are handling this....