Unfortunately Stefan, limb swaps are as easy as head swaps, I've done a couple in terms of customs and help a friend attach a couple of arms to figures he bought in a lot for his shop, One I used a reasonably crude method, Thing is It's actually difficult to do without damaging the part of the arm that goes inside the body because it has to be poked in while heated up, this of course damages it, the problem is, it's inside so you can't see, unless you whack him in some hot water and pop the arms and then check for damage (you can always put them back again) the problem with Tri-Fett's of course is that they are easily damaged paint wise and I wouldn't personnaly risk it.

Tri Fetts are awkward figures, take the paint scheme variations, dart and knee variations and COO combinations and you are looking at 30+ before you even take into consideration other variables.

In terms of paint scheme I tend to go with two, dark and light (conserning the three major colour used on the figures torso and limbs):
Dark - Dark Green Armour, Orange Limb Armour, Dark Brown Belt
Light - light Green Armour, Yellow Limb Armour, Light Brown Belt

Now usually these stick together with the exception sometimes being the green where sometimes the dark can be found with the light sceme and vice versa.

The thing with the dart is, the ones I've had/seen have always been with the (dark) orange paint which was your original concern Stefan, to me a limb swap is irrelevnt, because the apinted dart with the light yellow paint is unusual in it's self.

The over spraying or colour leaking is something that appears on many of the 'yellow' paint apps, but is not as common, or at least as noticeable on the 'orange' paint apps.

As for glossyness again, it may seem slightly off, but again I have ones the same.

Out of curiosity, what do you mean by 'the shoulder pad little lines?'

Also, one last thing you should check as a matter of urgency, does it have a remveable non sonic welded rocket?

I only ask beause I want to know if I still have the only one