Speak for yourself… I had to relevel Swann and Karax from scratch, back to Ascension. I was on a public account. Wanted to authorize some purchases of new COs, but they flat out refused, saying it’s too much of a headache to allow this. I made the fateful decision to revert to my old Sc2 account.
I wanted to relevel up Swann and Karax b/c they were still my mains. Swann with no tech Reactors, no Improved SCVs (to “pile build” buildings quicker), no Vespene Drone Harvestor. Really felt like the Dark Ages 
BTW, I ended up getting the formula, and calculating the “hard figures” below…
Karax was interesting… no Recon Beam, so his units would die eventually, and less so his towers. Then you have buildings like his Khadarian Monument that actually had a build time of 80. That exceeds the bt of capitol ships for crying out loud! No Stun Strike upgrade either for his Orb Strikes. That helps you and your ally’s units when engaging enemy waves, as it’d incapacitate a subset of them for a decent amount of time.
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What really eased the journey back into Ascension again was having both the XP boosts from CO bundle Stimpack, and the Warchests. +50% XP x2 REALLY did cut alleviate much of the “drudgery”