I'm a proud owner of a large shank Imperial - and currently not think about upgrading. Like the Sovereign the Imperial has some sharp 6th partials (the sharpest on my is the E flat), which is lippable. I use alternativ fingerings only when necessary (if there is a need for an accurate flat tuning, for example the F in D flate major). The sound is very beautiful, for my taste "warm and dark". Though, when playing with strings I prefer the smaller sounding Yam 321 for better blending.
Jochen
Boosey&Hawkes Imperial with SM4(U-X),
YEP-321 with DW 4AY ...
... and my cello