I'm very interested in the original question of this thread, the 4jr's. I've had mine for about the same amount of time as jqunac and, like him, have sometimes thought about better speakers. But anything physically larger won't work in my room, although larger speakers could make orchestral recordings sound bigger (i.e., more lifelike), which would be nice. Tightness of bass has been an issue for me, which I've improved in various ways (placement, bass traps, stuffing dacron in the vents) but am still not 100% happy with. I was a bit surprised to hear jqunac mention detail as an area to improve. I suppose there are more detailed speakers than the 4jr's, but they seem pretty darn good to me in this area. And every time I upgrade a source component I can easily hear the differences.
In any case, I'd really like to hear from anyone who had the jr's upgraded; what differences did you hear?
Thanks - David