Harbeth speakers definitely have a slight emphasis on midrange but I don't think we can characterize them as forward sounding. Other than the midrange emphasis, I find them to be very balanced.
Also, as @jjss49 mentioned, there is a substantial difference between SHL5 (non-plus) and SHL5+. I often hear folks making comments on the basis of owning the non-plus model. There is no comparison. I heard the non-plus version and own the plus version. The super tweeter in SHL5+ makes a huge difference. You simply cannot extrapolate based on your impressions of the non-plus model alone.