Very nice review. I bought the SF5s as a complement to the Sleek SA6s, my favorite IEM for the past half year. At first, I really liked the UEs, my first pair from the company. But as a the first week went by, whenever I used them out and about, I felt I was missing something, something the Sleeks seemed to deliver.
I did some AB listening, to the same tracks with the same sources, with the two, and decided that the Sleeks delivered a richness of sound that the SF5s just seemed to lack. Granted the UE soundstage is wide, but that wasn't it. I can't even describe it very well, but to me, the SF5s just sounded sort of flat, boring, by comparison. Granted, the Sleeks have an MSRP of $249 ($200 street), so maybe it's not a fair comparison.
Also, EdWood preferred the SF5s over the SA6s, but to my taste, the SA6s are a better choice.
Anyway, I do think the UEs are a good IEM upgrade for those on a $150 budget (I think you can get them that cheap now).