Over on the Support PC page I found this very interesting (especially the impact of playing the Guerrilla Mode), and worth re-posting in the general discussion section. Thanks Venom:

https://forums.ubisoft.com/showthrea...old-statistics

Originally Posted by venomgun1 Go to original post
I'm afraid statistics are tied to your uPlay account and outlive every campaign character. This data is synced with GRN (ghost recon network) and Ubi club. Only time partial character data is deleted is when ghost mode character dies. However, even in this case, certain stats like playtime will remain. Same is true for your store unlocks, once a pack or item is purchased, there is no undo button.

I assume the purpose for character deletion was going for the perfect tactical/stealth stat (100/100), right?

Tactical stat explained:
100% tactical stat can still be achieved by playing campaign or ghost mode with any existing character. Guerrilla mode will ruin tactical stat beyond repair though, first hand witness here. Fastest way to boost both stats is to hunt convoys from 500+ meters using a cheesy tactic - mark it with a drone while convoy is in range, use rebel spotting, then mark and sync shot drivers and finally all remaining survivors. After everyone is dead or despawned (usually 650+ meters away from your current position, it's buggy since the latest update), claim your prize ... or not, up to you. In tier 1 mode there will be a significant Unidad presence around convoys, so watch your six, this can be a stat killer, but it's also a huge resource of tier points. Basically, tactical in stealth means no visual detection as much as possible and killing through sight/scope only (no hip fire kills, since hip fire kills go against tactical stat). Loud missions benefit from fast hit & run attacks and destroying outpost equipment like alarms, power generators and SAM launchers. For prolonged firefights, setting up a good ambush will be crucial in maintaining the stat. Bait and switch also works well.

Stealth stat explained:
Improving stealth stat requires that every killed target is marked by binoculars or any drone before execution. Hip fire wont damage stealth stat. Marking targets for sync shot with your weapon will also go against stealth stat. It has to be done by binoculars/drone only. Using a compensator instead of suppressor wont affect stealth stat at all, but it will help greatly in increasing accuracy stat too and more importantly - not missing your target. When a mission goes loud, either by accident or it's scripted that way, loud portion of the mission wont count against stealth stat. Also, I highly recommend turning off team AI for any planned stealth infiltration, because any of them can (and will) mark any previously unmarked target and this will go against stealth stat.

Doing this will eventually feel pointless, unless you're also leveling up your character all the way to tier 1. In which case you're getting better stats while leveling up, gaining more prestige credits (for first level up), unlocking cosmetic items in inventory (including weapons, vehicles, etc ...). Hope this helps, good luck in your stat boosting and remember, team AI is not your friend! Enjoy your near perfect stats until you discover the joy of helicopters with miniguns and rocket pods