Garbage collection

Since WoW has garbage collection now, is there any advantage to doing clean installs after years of using the same WoW folder? I'm using the same install from MOP still and it seems to work fine but just built a new computer and debating if there's any reason not to just copy the several year old folder over.

I like the idea of having everything installed fresh for new PC but if garbage collection, scan/repair feature works close to flawlessly, then a new install really accomplishes nothing now?
You can copy it all over. Just delete the Cache folder and WTF\Config.wtf after you do so it doesn't import the machine specific settings from your old comp.
Or copy only from ...World of Warcraft/WTF/Account/ on down.
Garbage collection is about clearing memory allocated by addons and no longer used while playing the game. An updated game or brand new install won't make any difference if they are the same version. Updated addons or brand new installs won't make a difference if they are the same version. Garbage collection wise.

The addons you use might.
Thanks! there's always the notion that fresh installs make everything run smoother, but if the WoW client maintains all your files outside the addons identical to fresh install it'll save me time from doing fresh installs. Between WoW, OW, Diablo, HOTS it's probably a couple hundred G.
If you are talking disk space then a fresh install can save you some as it doesn't come with all the uninstall files each patch accrues (possibly up to a couple of GB), saved settings for unused addons (not much at all relatively speaking) etc.
yea the disk space doesn't really matter anymore since a few GB here and there with the size of today's SSD's will never really add up. I splurged and got those cheap Micron 2TB SSD's to use as a storage drive (down to under $250 with BF prices) and a dedicated NVME 500GB apps only SSD so I don't think I could fill it up if I tried. It's finally gotten almost cheap enough to go SSD only other than hard drives for long term storage.

I was only concerned about load speed/smoothness if 7+ years of using the same folder would have any impact on it with hundreds of modifications to the files patch after patch. If the scan/repair and garbage collection basically syncs my files to be identical to every other WoW user, having say 10% or so of wasted space wouldn't bother me.