I wouldn't hesitate in getting a 4/4 Sigma - I had a Sport in 2009 and put 24,000mls on it in 4 years and it was perfectly reliable. There is another guy on here called Jeremy (WR142LL) that uses his as a daily driver and when he last surfaced on here about a year ago had put about 70,000miles on his.
The M3W has had a myriad of problems the latest of which is cracked main frame. These are proving to be very expensive ownerships. For confirmation just check the Three Wheeler threads, I wouldn't entertain one until the factory has the whole package thoroughly developed especially for a daily driver personally however exciting they are to drive.
Worth a read through this thread.
http://www.talkmorgan.com/ubbthreads.php/topics/438058/1 
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