OK, I'm favouring another round of schematics and doing one of the following:
(A) Immediately upgrading to a fresh 1.8.1 world (my recommendation)
Pros: That will sedate the increasing restiveness players have for a bit, which has gotten almost out of hand. Also, this version has been stable for a while now and mods are mostly there (even one that adjusts the server jar to disable XP orbs).
Cons: May have to move worlds again come 1.9, assuming the recent pre-release's bugs. May involve one or more 'fresh starts'.
Misc: I'd leave it up to the users to determine whether they want to continue working on their older structures, but ultimately it's you two's decision on even giving that option (I say don't). Also, we'd have to temporarily add snow blocks to the list of stuff that can be obtained from Ops upon request.
(B) Retain 1.7.3 until 1.9 + Bukkit arrive, and then make a fresh world (Strafe's implication)
Pros: Less overall work to do than the above; no issues with terrain generation or fresh starts
Cons: Instigates more restiveness, mostly in the form of waiting. Who knows when 1.9 will arrive?
(C) Retain 1.7.3 until 1.9 + Bukkit arrive, but keep worlds (Stuffman's suggestion)
Pros: What need for schematic work (in short-term future)?
Cons: Rest of the lot will be boring themselves to death until then, and the map file is already ridiculously large. We also may need to do schematic work regardless if 1.9 does have adverse effects on existing chunks, but by the time we notice it may be too late. Also, once again, unsure of the arrival time of 1.9.
(D) Regress to 1.7.2 (if one can find both server and client jar files) for a bit
Pros: We can crash the diamond supply again :getdown:
Cons: Pretty much everything else
(all options also assume the re-adding of Essentials, but Multiverse is left to you two, though I am recommending that)
Also, I've noticed - the TF2 server is run on a general web server host (according to its Op omgkitties), but the MC one uses a dedicated MC one. Granted, I know there is tech support in that option, but it doesn't seem like it has been too reliable.... Assuming configuration and whatnot is not a problem (and tweaking is an option), I'd give some thought into that possibility in the long term if host rigidity and lame responses become massive issues (or worse, implodes AKA Brohoster). Major catch with that - we'll have to do all the configuration ourselves (plugins, server RAM, HDD, bandwidth, Mono, MCMA maybe, etc.).