Have just bought a Sony BC-M50 V-mount Ni-MH and LI-ON Lithium-iom dual battery charger. What V mount batteries can I charge with this? Is there a limitation on the wattage of the battery I can charge? Am now looking for suitable batteries to power an Ikan IFD576-S 2-Point Light Kit with Sony V-Mount Battery holders. Need about 2 hours use per charge.

I charge Bescor V-loks on an IDX charger. Shouldn't be a problem. The charger can't read so it doesn't see the name of the manufacturer of the battery you're putting on it.
When I used my beloved Anton Bauers years ago I charged everything from 50W NiMH to 120W MiMH and 90W LiON.
I can't guarantee but I'd be willing to say that based on my experience you should have no problem charging your batteries on your Sony charger.

Was curious about this because when I searched for this particular charger, I couldn't find it. From this I assume it is an old one, but even so, should find some reference somewhere to it.

I Googled it and found a bunch of links but I think you're right, it appears to be an older model. You should still be fine charging pretty much any V-lok on it though.