Shower mixer bar - concealed backplates?

[outmyway]

Has anyone experience of using these mixer bar back-plates?

http://www.tapsbiz.com/aqualisa-sho....html?osCsid=j9jh6k4lu388337bq4ujd90r53ltb6rd

I wondered how sturdy they were, are the threads metal?

These look better, but prefer push fit connectors rather than compression to use plastic pipe with ...

http://www.screwfix.com/prods/51167...r-Fittings/Grohe-Conversion-Elbow-BIV#reviews

 

[dextrous]

Personally I'd go for the compression fittings. Never use these plates myself (just use garden tap wallplate connectors, but the principle is the same), but look worth the effort for time to be saved.