At our altitude, I think that brushless is an unrequired expense. The heli has a bunch of lift without the extra punch. Some like to 'get it all' and for them there is nothing less that will do.
To help feed your alloy habit, here's a link http://www.geocities.com/pierrehollis/mh3.htm You may find something useful there.

If you are going to the Walkera and it's the same as a Falcon 40 which is the same as an EF Sabre, I can send an information document to you if you like. It's from a friend in Albuqueque - about a mile high with thin air. He has some tricks to allow him to fly at that altitude as the stock heli won't lift out of ground effect. It's nothing earth shaking, but you may find parts of it useful. I'd post it here, but this is the wrong forum. PM me with an email address and I'll send you the document. I think that most of the stuff mentioned is available from Michael.
Soloboss