Looked at Fiat and Mercedes base for the Hymer. On balance we actually preferred the Fiat in the latest series 8 guise.
There is substantially more room inside as the sides pf the van are pretty much vertical rather than being tapered inwards, and the most is quite a bit shorter giving more habitation space for a given length.
We have the Blue Evolution (a posh Hymer Free 540) and there is SO much space - we transferred the contents of the Cali across and there is still tons of spare space, its quite amazing really.
The 540 works for us as we can still use it as a second car, being easy to park in a normal space and manoeuvre being a short wheelbase.
Cant fault the Hymer fittings. The Fiat dash is, well, a bit Fiat, plastics not as good as VW or Mercedes. The seats however are very comfortable and adjustable, and the digital dash, 10 inch display look really up to date.
Need to upgrade the speakers and add a sub though and we may go for VC or Goldschmit air suspension.
We used Highbridge near Taunton and they have been really good throughout the process and I'd highly recommend them, in particular Adam Green in sales.
I'll start a new thread and review the van, but did upset a few people before who didn't like the idea of non VW vans on the forum which was a shame!!