Historically, Tunze are the innovaters when it comes to SW equipment. They were the first to bring in propellor based powerheads with a low head and wattage and high water turnover rate. They also made the first powerhead designed for aquarium use and designed and sold the first protein skimmer that utilised venturi rather than an air pump to get air into the skimming chamber.
They have recently been the first to introduce a mass water movement device (the wavebox) to simulate the effects of waves breaking across the reef.
Their price is somewhat high, but their quality is second to none. That is their chosen way, preferring to design for the premium end of the market for people who want the best. They are the only manufacturer that can compete with Eheim for longevity and reliability (their nanostream range is the first range of powerheads made by machine and not hand).I currently use two 1001 powerheads on my FW tank for water movement. They proudly state Made in W Germany indicating an age of at least 17 years.
I have found the skimmer fine, adequate flow around the skimmer inlet/exhaust will prevent massive overskimming of the same water. RC notes it is comparable to a similar priced Deltec (the benchmark against whom most simmers are measured) in performance.
The new Tunze Nanostreams are competitive in price. If you look at the price per LPH of the NS against Hydor's koralia, there is little in it, and the Tunze is cheaper on electricity. The downsid to the NS is the weak fail point of the holding bracket.