GoA: Right. comparing card by card in vacuum Sage is a more versatile one. However if I don't play Bellower, don't care about color splashability in a dual colored deck, don't play grapple, meanwhile if I have 6 T2 mana dorks for potential T3 LD, the LD possibility may be better than the 2/1 body in this particular deck? I will test more.
The problem with testing this is you can't get verifiable statistics unless you also know what your opponent has in hand. So the testing conditions here would need to be you playing against a buddy who can take note of his/her hand starting from when you first cast Mould to see how often the LD is relevant.
You'd need to keep track of;
* Number of times you LD a land and it prevents opponent from casting a spell that's not merely convenient or on curve, but might have swung the game for them (sweeper, removal for one of your key critters, etc.)
* Number of times you LD a land but it never really slows them down - sure, they might be a land behind curve, but they can still play relevant threats and/or answer yours. This will come up a LOT when opponent went first.
* Number of times you LD early and opponent never gives you any cause to regret it.
* Number of times you LD early and opponent plays a better target (more annoying land, more swingy artefact/enchantment) before you draw another copy of Mould (and number of times you have a second copy ready.)
* Number of times Mould is effectively blank (opponent sees no art/enc cards and plays either no annoying nonbasics or is never short a colour)
* Number of times Mould is the decisive card in your victory (which will overlap some with point one.)
* Number of times you use a card to recur Mould that could not recur Sage, or number of times you could have recurred Sage if your Mould-recurring card had been Grapple or another card that returns permanents from graveyard to hand (or a bounce effect if the deck you're testing runs any.)
* Number of times you use Mould in a situation where Sage would have worked, as well as number of times you used Mould for an art/enc and Sage's body would have been relevant for any reason later (chumping, piloting a vehicle, any effect that counts the number of creatures you have like Nissa's -2, etc.)
I think when all is said and done you'll find that yes, Mould will have a few situations in which it either does something Sage couldn't, does it better, or otherwise has an advantage, but I think you'll find Sage's benefits outweigh Mould's most of the time - unless you specifically include other LD effects in which case the cumulative LD effect may be more overwhelming/relevant.