Aragorn,
It shouldn't make much of a difference. We live in a highly capitalistic society where big labels charge big money for their products. I'm as much of a sucker as the rest, I spent $70 dollars last week on a pair of Levi's because I like the name. Denim is denim, isn't it?
In answer to your question:
MVP is as you say, moisture vapour permeable. As of today, there are two seperate schools of thought in regards to WPB (waterproof breathable) membrane garments.
1) Microporous garments: These include Gore-Tex, Columbia's vaunted Omnitech, and I believe Mountain Hardware. The membrane contains billions of microscopic pores that are too small for water to enter, but large enough for perspiration to escape. Other than the limited useful life of DWR (durable water repellency's) their only drawback is that the pores are easily clogged with dirt, grime, and sweat.
2) Monolithic: Other than Burlington Industries XALT and Peter Storm's outwear, I don't know another company that uses them. (If anyone does, please let me know!) They're non-porous, and work by a hydrophobic/hydrophillic reaction that occurs in the membrane. Don't ask me to explain it, it's too complicated to type out after a long day!
Essentially what I'm getting at here is that it shouldn't really matter what sort of MVP garment you're purchasing. Gore-Tex doesn't have quite the market monopoly that it once did, and there are innumerable smaller garment manufacturers out there charging far less for an equally useful product. Heck, I don't even use Gore-Tex anymore. My current WPB garment is made by Toray Entrant, and as much as I prefer Ventile, Entrant does a better job at keeping me dry than Gore-Tex and the jacket was a sight less expensive.
I hope this helps.
Cheers,
Adam
