Given that their background is in Fiats and VAG is "new" to them, I think I'd rather go with a company that has more of a VAG background. As far as I know the PD engines are different from any other manufacturers engines as it's a VW only technology, I'd rather know whoever I went with knew these engines like the back of their hand.
There's no prices on the MAS performance site that I can find, I had my Leon P-Torqued and it was well worth the £215 I paid (group buy price, normally £265). It's a bit of a drive but Will has a top reputation with a lot of VAG owners and I'd rather use someone like that than a little known company who are new to the field. Just my opinion of course