I can tell you- I've weighed the assemblies, and the 122A is heavier than the 129H assembly. Can't remember the exact figures, but it was by around 10 grams or so... that order of magnitude difference.

So, I would agree with keeping the original cone... especially when high-quality edge-wound coils are now available in the aftermarket. In the old days, it was a choice between a factory kit (with a proper edge-wound coil) or an aftermarket kit with a round-wire coil... this is no longer a hard-and-fast limitation...

Regards,
Gordon.