Hi Tim,
The more I think about it the more I'm inclined to go with the Power Sword and Storm Bolter combination as par the first link... However I would still maintain that he'd choose the weapons for the job and he's been fighting for at least 200 years, so will be very proficient with whichever weapons he wields!
Combi-Weapons are better than Storm Bolters, I don't see any reason why he shouldn't wield one... (especially since Storm Bolters were originally Combi-Bolters, which were two Bolters strapped together)
I think that Combi-Melta actually has the least value for Terminators as they need to be within 6" to shoot effectively. If they're within 6" then they are within charge distance where your Powerfists, Chainfists (which are basically Melta Bombs) and Thunder Hammers can do more damage... (The Combi-Melta makes more sense on Tycho and Dante precisely because they are unlikely to be accompanying Terminators, therefore are more likely to be in a squad which threatens tanks with Meltaguns)
The Combi-Plasma allows you to do a lot more damage at 12" than your Storm Bolters, plus won't change what you're shooting. As in if you're hitting infantry, the Plasma does it better than your Storm Bolters, and if you're hitting tanks, it works as a slightly worse Cyclone Missile Launcher.
The Combi-Flamers will always be useful, especially against large groups of infantry, which is traditionally something Terminator heavy forces struggle with...
(Combi-Grav would be awesome if you had access to it!)
I believe you could magnetise the Combi-Weapon which comes with the new Tactical Squad box set, as I think it comes with a bolter and then the four combi options... But I haven't bought it so I'm not certain...
Slick Samos