I have both a mono and a para, with a well set up Ohlins on both there isn't a lot of difference, and the reliability of the mono seals it for me, but the GS can be improved slightly at considerable cost, if money doesnt concern you.
FWIW a paralever acts like infinitely long swinging arm, so from a handling point of view there is no advantage in a longer para, unless you are like to ride off the end of tables , etc, etc, like most of the folks who have fitted them - Utube has all the details--------.
G/S forks will be worn enough by now to need a billet top triple and tubular lower brace, but dialed in to suit an Ohlins are good enough for the rest of the bike.
My GS has HPN inserts which suit the stock Ohlins perfectly, and no one who has tried them claims to have anything better - in fact one guy actually removed his USD set up and went back to stock dialed in to match the HPN.
I have never had the slightest trouble with the stock charging system on any of my bikes over almost half a million k's, but I do stick to the rules.
EME has good quality Valeo knock offs which have sorted out the weak spots of the old ones, I have 200,000 trouble free km on one.
Both starters and charging systems like a good battery, a top quality AGM should be the minimum, and dont wait on it failing-----.
FWIW there is a guy on ADV who has enough of the long green to have had several wankmobiles built for him by lauded demi gods , both in the US and Oz, and his advice is to fit an Ohlins and forget the rest.
Metz Enduro 3s are the best of the 50/50 tires i have found if you buy tires for grip, not for their looks, TKs among the worst I have tried, mediocre everywhere. Anekee 3s come in GS sizes and are excellent too, but no mud or sand!
My G/S stops OK with the stock caliper, 11mm master cylinder and EBC hh pads, but it isn't hard to lock a 90 mm 50/50 tire!
I like the big G/S tank, I think it actually improves the handling , and it is nice not to have to plan your day round petrol stops, but even in Oz you dont really need the 600 km range between fill ups.
By now most G/S wiring be past its best so factor in the cost of a new harness and the other 20 or so bits that complete the system.
I have 1000 factory barrels and pistons on my G/S with a Boyer Micro power ignition system and it makes enough power for the rest of the bike.
Mikuni carbs might work better than stock for some folks, but there are dozens of different set ups out there, if you spent the same time finding the best set up for Bings youy probably wouldn't find as much difference.
Bit like the fancy fork swaps, I suppose--------------.
Hope there is enough room on the furum far an alternative point of view------------.