ARAM changes will be good.
I am an avid ARAM player, I wouldn't say I'm "pro" at ARAM but I play it a lot. After reviewing the slotted changes, I think they are overall positive and here is why.
Re-roll changes This is a double positive. Not only does it prevent people from re-rolling your favorite champions; this changes prevents you from ever re-rolling into a downgrade. Now if you re-roll into a worse champion, or a champion that makes your team unbalanced: you can switch back to the previous champion thus making it impossible for a reroll to be bad.
Increased Free rotation champion pool This change is a clever answer to ARAM smurfs, which only have favorable champions and the reason you see Veigar and Sona every other game. With the increase in the possible champs to roll, it make ARAM more inviting to new players who want to try out champions as well as a clever answer to ARAM "smurfs".
**Base gates (skill only changes) **If you have a superior computer; you will load in faster playing League of Legends. If you load in faster, you can get to an ambush point faster. Limiting movement at spawn; evens out this load time lag and makes for a more fair game overall.
Surrender Times Reducing the surrender time is a nice quality of life move on RITO's part. ARAM games are typically shorter then summoner's rifts and can be so unbalanced playing frustrates the players. RITO said they're considering doing remakes, but want to cut back on intentional DC and AFKs. Maybe in time they will think of a clever solution to this, such their solution to ARAM smurfs.
Dark Harvest Nerf This change is much needed, as it will help ARAM player on 2 levels. 1st, this will stop overpowered scaling which can occur when some champions out scale too hard with dark harvest ex: Zoe. 2nd, this reduces the amount of teammates willing to take Dark Harvest to troll for the memes as Dark Harvest is now less viable.
Warmog Removal This is a fantastic development, and balances some late game tank imbalances ARAM suffers. Removing Warmog's does leave a gap of healing which some champions ex: Soraka greatly benefit from. Alternate builds will need to be found, or new items, perhaps a cheaper Warmogs that loses its effect late game.
Limited Time Items
_Ghostwalkers A pair of boots that only melee champions can buy which let you walk through walls _ This item is going to be very fun, and is said to mimic Kayne according to the linked article.
Spectral Cutlass An AD/Lethality item that, when activated, marks the ground beneath its bearer. A short time later, that bearer is automatically returned to the mark. This item is going to be amazingly fun for tanks to feign going all in, as well as assassin class characters.
Bloodletter’s Veil A close cousin of Banshee’s Veil, this AP/Magic Penetration item shields its owner when they do damage with an ability. This item seems extremely strong, and can be good on tanks but seemingly broken on champions with AP damage.
Health Pack Changes Instead of a singular health and mana boost, the health packs now activate a healing rain type ability which both teams can benefit from. Not only does this change add a new strategy, it also help protect the team form greedy players who take health packs unnecessarily.
Overall, looks great RITO. As an ARAM player, I'm happy.