This was discussed recently in a tackle shop i was spending too much time in. Very interesting discussion and the general feeling was that balancing a rod and reel on your finger is an old myth, from the days of brass reels and cane rods.
1. Rods will cast very well with no reel attached.
2. Do you cast with your rod held horizontally?
3. A heavy reel actually causes casting faults as it encourages the wrist to "break"
4. The reel will be balanced on the rod at different points depending on how much line you have on/off the reel.
5. When casting, it is the weight of the line that matches the rod, not the reel.
Personally, i think if you find an outfit that suits you and you are happy with then go with it. Most of my reels are very light on the rod but this is just personal preference.
Maybe a casting instructor like ben D would be able to have the definitive say??
Or even a certain Mr Barrio who designs fly rods?