They have access to their own economic system "Efficiency Studies", which gives the same racial bonus as the usual econ-techs (Xeno Economics, Banks, Republic-Federation). And these techs do have lesser cost and are sooner accessable, and that taken together with their +10% stock bonus is one side of the advantage.
The other advantage is that they can mine out resources pretty well - given they have their hands on some econ-resources can make a real difference.
However, they only have one econ-improvement, the Efficiency Center, the Yor's equivalent of a Stock Market. Although also very early accessable, it's only a one-per-planet building... and that's a huge loss.
So, if you're playing without tech-trading/-brokering or -stealing, you won't be able to create ÜberEcon-planets - which do naturally require a high population, which is also not really doable with them. So, thinking about "specializing" planets for production/research only is not really fundable.
Although their Stalks are very interesting structures in that they combine pop & moral - 2 Stalks 3rd grade give 6b ppl & 40% approval, while a combo of Advanced Farm/VRC gives 7b & 40% - 1b more. However, the Stalks are much faster researchable... and that's somehow a red line in the Yor's techtree - they are really strong from the beginning on while later become gradually weaker and fall behind compared to other races.
The same could be said from their labs & facs as well.
And while the loss of moral-tree can be mitigated by some well-outmined moral-resources, a high pop is generally not needed when playing them. If taken everything into consideration, the Yor are played best when they colonize a lot of planets, irrelevant of PQ. But they need to focus to have their planets in a status of low maint, and that's why their initial facs and all their one-per-planet structures are best. I'd even go so far as to leave tiles open on high PQ planets, their planets look virtually all the same, Starport, Research Matrix, Efficiency Center, a Stalk and as much facs you can support.
But if you leave techtrading etc on, this can pretty much affect the whole gameplay, because once they'll get their hands on a good reproduceable econ-structure they can fill in those empty tiles with them - which gives enough power to upgrade their facs to another class - their endtier fac has the highest base MP output in the game.
The only downside is that they somehow lack the diplomatic tree, so techtrading is not that easy. However, most other races diplo-/moral-/econ-techs are tradeable - while theirs generally NOT... so, if you then compare the Yor's economy in full combination of own + alien techs, I'd say, they pretty much beat everything else out there.
