This is a funny or strange situation, it seems the more you know about the practicalities of cars, the more you worry about things.
I too am beating myself to death concerning if I should change the coolant in my 2011 Audi S4, it too has some issues to consider including an extra electric pump that only runs under certain conditions and supercharger coolers to bleed - oh and the plan seems to be to buy new bleed valves/plugs, so sounds like these plugs might not come out easily!
Okay, things that I've found out so far:-
1) there was a "line in the sand" time wise when the coolant type was changed at the factories for VW and SEAT the other marques seemed to be a bit vague about that date, after that date G13 use was stopped and G12E (G12 evo) replaced it, so in the parts listings this fact is reflected on which coolant that car should be filled or refilled or topped up with - although as usual each newer coolant type is backward compatible at least to G12.
2) again sourced from the parts listing, the coolant header tanks were not undated because of this, so I'd guess they just exhausted supplies of the G13 marked tanks before starting to use G12evo marked ones, which from some of "my" cars I can see is true - same when moving from G12++ to G13.
3) supplies of coolant G13 or G12evo, I'm getting the impression that for everyone's convenience, VW Group parts departments just exhausted G13 stocks and now only stock G12evo - although you could probably request that they sourced G1from the warehouse.
4) factory filled ready mixed coolant is mixed to give -35C protection and I would want to stick with that mainly because of the higher concentration of corrosion inhibiters - some online VW Group dealerships are selling ready to use coolant to G12evo spec but mixed to a lower temperature level, maybe only -25C - so that will be cheaper.
G13 legacy used only
G13 A8J M1 Conc 1.5ltr
G13 A8J M8 Conc 60ltr
G13 A8J M9 Conc 210ltr
G13 744 M2 Ready Mixed to -35C Protection 1.5ltr
G12E current use
G12E 100 M2 Conc 1.5ltr – only listed under SEAT!
G12E 100 A8 Conc 60ltr
G12E 100 A9 Conc 210ltr
G12E 050 A2 Ready Mixed to -35C Protection 1.0ltr
G12E 050 A8 Ready Mixed to -35C Protection 60ltr
G12E 050 A9 Ready Mixed to -35C Protection 210ltr
G12E 040 A3 Ready Mixed to -25C Protection 5.0ltr
That last G12evo ready mixed for down to -25C only is being sold by "coxmotorparts" on ebay for roughly £28 for a 5ltr container
I've always found the colour differences of the different G12, G12+, G12++, G13 genuine VW Group coolants to be not too obvious, possibly the same for G13 > G12evo.
Anyway, back to your original question, I think that the plan is to empty, flush place under vac and refill then run the engine while activating the electric pump and any electric valves in the system to allow full flowing of the new coolant and clearing of any trapped air, I'd think that a DIYer could achieve a good result though it might take a bit of time, maybe cracking open some extra rubber pipes for venting and using VCDS etc for activating the system electric devices.
So, I'm still sitting on this one along with "how many years or miles" is the factory filled coolant good for, any testing that I have done with CoolTrack coolant test strips type sticks and refractometer, on all "my" cars claims "all is good".
Edit:- sorry the lists of G13 and G12 scramble up when I save this posting, but if you move them out to their two columns it will make sense.
Sorted!
Edited to change “G12” to “G13” at one point.