Other than volume, what more can you adjust on the Manley? Now you can adjust things easier by not having to take the cover off the BAT...
The BAT VKP10SE with depth charges is a hec of phono stage. However, the newer Io mkII Sig will beat it. I've heard it numerous times at 2 friends houses. One friend went from a Manley to the Io mkII sig dual supplies. If you want the best, get the Io. If you want something that's much more plug and play, the BAT is a pretty good deal.
I've heard that same comment on the Manley, diff tubes or cartridge matching should help out. The BAT has the classic BAT sound...incredibly wet warm mids, big stage, deep tight bass soaring highs. The mids and the top end on the BAT may compete for best of class. The Io is better at inner detail, image size, flow, etc. The little things that mean so much.
The BAT does benefit by running it balanced, both input and output.