Having listened to a few UTAU songs in English, I don't "feel" any love for it.
I agree it has potential for some clear sounds, but UTAU has always been a "hard" engine noise, whereas Vocaloids has always had a more natural tone, therefore, is slightly softer overall no matter what the bank. And UTAU's engine noise is unrealistic still in comparison to vocaloids.
But... I want everyone's opinion, not just on English UTAU, but UTAU in general... How good is it "language-wise" exactly, do you feel? I've heard some "good" vocals and some ones I felt needed more work, which is typical of UTAU. But due to not being a UTAU fan nor caring for it since I own several Vocaloids myself, I don't choose to work with it at all. This does not mean I'm not curious and this is part of that curiosity. :-/