The process as you describe worked for me. I moved from londonfgss.com to lfgss.com (as the users called it that anyway and it's nice and short for twitter URL

The process as you describe worked for me. I moved from londonfgss.com to lfgss.com (as the users called it that anyway and it's nice and short for twitter URLs and for mobile entry). Before the move I had 600,000 URLs indexed, 1 month after only 100,000 URLs, 3 months after 600,000 and 6 months later I now have over 1,000,000 URLs indexed. The only thing that has happened is the pagerank hasn't apparently come over. But this is probably just the pagerank indicator rather than an actual loss of pagerank. The 301's, the GWMT change, the 1 to 1 mapping... all worked really well. That's just my experience, but anecdotally (for you) it does work.