I would say that changing to the BAT VK-5i would give you the biggest improvement, that is unless you enjoy the crystalline sound. By that I mean that the BAT will make the sound warmer, richer, more full, but you may lose a little detail in the highs. The Meridian would tend to keep you in the high definition camp, if that's where you want to be. I tend to lean towards musicality over detail, but I know others have different tastes. I hoped this helped more than confused you. Only you know your musical tastes. Are you looking for more musical warmth or more detail? Get the BAT if the former, and the Meridian if the latter.
Happy Hunting,
John
Happy Hunting,
John