@BandsWithOthers I've always been a sucker for tutors ever since the olden days of Burning Wish-based combo decks; the flexibility that they offer is something I honestly really appreciate. Yes, that's actually one of the things I noticed - your first PO really requires you to find either more mana+Draw7 or another PO, with Mystical+Vamp adding redundancy you end up with higher odds of hitting one of those spells that assist you with continuing to go off, and as you said; with Probe they become essentially 1-mana Demonic Tutors for the purposes of the deck.
The downside is of course, that they open you up to Mental Misstep which a low-tutor variant of PO is far more resilient against. On the other hand, it does mean that in g2/g3 if they have not seen your tutors yet, they are less likely to have the Missteps; if they have - perhaps they have boarded in less more disruptive and disastrous hate.
I definitely have not missed LED or Chrome Mox. Chrome Mox was probably close to 80% of the time just an Ornithopter that can't chump block, while LED as you said - was useful for mana in a very rare situation. Primarily either with a hold-priority Draw7 or YawgWill. Missing them hasn't really made me feel like I have less colored mana in a noticeable way. Mox Opal really puts in overtime on that regard and the hands where you don't have it feel quite a bit worse.
The reason I like the 2x Monoliths is along with Mana Vault, they give you something to do with Key outside of the Infinite Turns combo. Being able to use Key to generate those excess levels of colorless or filtering the colorless from monolith/vault/crypt into colored with Moxen has been quite often a crucial interaction.
I could definitely see running a 10th land. Tundra for Fragmentize is interesting. I do think that a second answer to turn 1 Sphere/Stony Silence/Thorn is a way that the deck could be tuned a bit to be able to actually win games on the Draw. Though, I've found that quite a bit vs. Shops the tutors are off finding me Chain of Vapors - which helps a bit in regards to dealing with a quick hatepiece, it's usually too slow vs. a Shops deck that is on the Play as they can follow up the first piece with either another tax effect or a Wasteland (or both), then you are guaranteed to lose.
So yeah, game 1 it's generally tutor for Chain unless I have the Force for it. Of course, the best is simply being on the Play and turn 1'ing the opponent, which the deck definitely is likelier to do than any other Storm iteration I have played in the past.
One of the cards that I'm most skeptical on keeping in the deck is actually Desire. I like the package that you get with Tinker, especially vs. Shops where you can bring in a Blightsteel Colossus for the quick win even thru a tax effect - but Desire has usually just been a very win-more card. It's a bit too hard to cast as your opening spell, while if it's chained into from multiple POs; you were very likely to get there with any Business spell.
It definitely is like you said, a poster-boy for what people THINK of Vintage when they don't play it a lot. An almost Highlander pile of busted restricted cards that Tendrils you for 50 copies.