They look to be constructed very well. I dig their inner-locking system, it's very similar to the wall I have.
The LED chips are all right (I'm a huge fan of the SMD3535 for 5-6mm. The SMD2727 seems to be working well these days for 3-4mm)
Nice looking refresh rate.
The weight seems to be a bit on the heavy end (the problem my current wall ran into a couple of time). I'm spec'ing a new wall and i'm trying to keep my weights to around 12-14lbs for a 500x500. When doing large shows with 200+ tiles, the actual show's structure and lifting points become an issue as they won't support heavy walls (10,000+ lbs) so cutting the weight of each tile will allow for bigger walls, which means bigger shows and bigger clients
Is it IP65 rated?
Not sure what your application or company size is, but these are all the factor's I'm currently looking at for my next purchase this year.
Also, is there an office located in your state/country? I'm in the USA so if there isn't a USA office, I don't waste my time. I do a lot of repairs in house and will need a local office to ship my bad parts to so I can get credit on new parts they ship me. International shipping and custom's holding time is a nightmare and a lot of money if I have to do 3-4 shipments per month.
Couldn't find any info on the Strong 4