It might work out, but it really depends on what the average citizen thought of the ship. If they see the original as a failed project and fruitless endeavor, you definitely want to give it a new name/appearance/statistics to distinguish and distance it from the original as much as possible. On the other hand, if it appears as a heroic vessel that concluded the NTF war and took down a number of Shivan destroyers with it, do the opposite. It is quite likely that they will try another "joint project" sometime, but whether it will follow the same design as the Colossus is questionable.
As for the Myrmidon/Helios thing, that was definitely unintentional. They probably intended to put in the Harpoon instead, for which there is no reason that a highly versatile space superiority fighter should not be able to carry; this thing is the best all round anti-fighter missile, so the Myrmidon should definitely have it. The Helios is not a standard-issue weapon at all and is only used in the most critical situations, and only the largest bombers in the game can carry it anyway.
Actually I'll bet it was an easter egg. Not very many missions in the campaign let you arm the myrmidon with Helios, simply because one or the other isn't available.
Yeah, actually there is no campaign mission at all which lets you do that; the only official missions where it can be done is in multiplayer, which are tweaked quite differently gameplay-wise.