Athene's got completely gutted

Here's the new stats for Athene's Unholy Grail:

2700 gold 60 AP 25 MR 20% CDR 50% mana regen Increases mana regen by 1.5% of your missing mana.

Now let's compare it to Morellonomicon:

2100 gold 80 AP 20% CDR 100% mana regen (WOW)

I did the math, and I came to three conclusions:

1. After the 4.20 patch, the way that mana and mana regen works is such that mana scales harder than mana regen. What I mean is, when compared between a champion's level 18 and level 1 stats, their mana difference will be greater than the mana regen difference. Morellonomicon scales with mana regen, whereas Athene's Unholy Grail scales with both mana regen and mana. The problem with this is that Athene only provides 50% of base mana, whereas Morellonomicon provides 100% of base mana. The rest of the mana regen from Athene comes from mana font, but how good is it exactly? I think it's worse than the previous mana font in all aspects. At 1000 mana, you get 15 mana regen, which is fine, but this is true when a) you're at level 18 and/or started with a tear, and b) you're very close to being OOM. And by the time you are close to being OOM, it doesn't really matter anyways because you won't be able to spam spells even with your Athene's. On the other hand, when your mana is at a respectable level, Morellonomicon is the better choice.

2. Given that Morellonomicon = Athene's with regards to mana regen in most cases, what about the other stats? You pay 600 more gold (don't forget they decreased the cost of Morellonomicon and increased the cost of Athene's) and sacrifice 20 AP just for 25 magic resist and a mana restoration after a kill or assist (making it a more of a snowball-y item). Is it worth it? If you badly need the magic resist, maybe, but if you're a long ranged spammer, a few measly MR won't make much of a difference.

3. A Morellonomicon + a Tear of the Goddess now costs 2850 gold. This is only 150 more than Athene's. If you want to go for the mana regen route, this may be a far better choice, because you get a total of 150% mana regen and 1000 mana. Meanwhile you still get more AP than Athene's.