the main difference between bbh & sfh :
– requires strict & narrow overlaps between cell.
– limits the trx capacity per cell depending on the number of hopping frequencies available in the MA list.
– prevents hopping of BCCH trx
– requires heavy frequency planning (as much effort as a non hopping planning)
– allows hopping of bcch trx
– adapts to poorly designed network (irregular tilt, azimuth, environments)
In terms of frequency diversity (= coverage), it’s not the method (BBH vs SFH) but the number of freq (>4) that matters.
In terms of RxQual, the differences are related to the pros/cons above. I assume your network design is not adapted to “dumb” SFH but instead requires “smartly planned” BBH.