At the time we were looking to buy used and there weren't that many 2nd hand T5 Californias around then. LHD imports were a cheaper option and we got a very good deal on our MP. We looked at various other conversions but didn't find anything we liked as much as the MP (or California).
We have friends with a LHD Westfalia T4 who were very enthusiatic about their van and persuaded us that LHD wasn't that much of a problem at home, and of course better for european trips. After looking at both the MP and California we actually preferred the very solid feel of the Westfalia conversion. There were also reports
of various problems with early Californias, although the MP was more of an unknown quantity. I've still only ever seen two or three others in the UK.
Our MP has proved to be excellent though - over 10 years of regular use and it is really only the van itself which is now starting to feel like it is getting on a bit, as you might expect. The Westfalia conversion is holding up really well.