Squirrelloid,there are 2 reasons not to play E9N4:
1.Fun. It is always nice to play builds which ALSO work.
2.Niefelheim is a strong nation, but if it would be possible to have two Niefelheims and one would be with T3S3L3D3 build and another with standard, on normal game settings and 12 provinces per player map, I believe T3S3L3D3 would win. Nations with small sacreds or sacreds with 2 attacks , which benefit heavily from S9 or W9 or F9 or even A9 can benefit more. For Niefels you can add W6, + minor blesses or 1-3 points in paths which you don't have natural access through mages for sitesearching and summons.
If it would be possible to play "standard" niefel build and T3S3L3D3 niefel build on a map with 12 provinces, I think player with standard build would have less chances to survive.
So the question is not "is the standard build is good?" but in what situations T3S3L3D3 build is preferable, or does this build create enough power initially to cover longterm looses (some if them can be managed though).
WingedDog, as classical example with this build with enchantress (not sorceress

)can be Kailasa. Enchantress is good for strong or average E,A,S bless. Your sacreds are cheap, you can summon sacreds, bless benefits your sacred commanders.
As for great sage. I play only CBM. It's all about points. I like enchantress because is all most of my games I take E9, and enchantress has basic E and S points.E is the most popular 9 bless, S is good for lategame, for opening astral for some nations, S4-S6 bless is useful for any kind of sacreds, S9 is also not so bad, for such nations like Atlantis, Lanka (helps Lanka against tramplers as well!) and many small size sacreds.
And better bless, or better sitesearching abilities which gives you sitesearching path in paths you don't have natural access to, are more important then extra 5-10 points of research.
Any nation which can bet on summonable sacreds or sacred commander thugs is a good candidate.
As for little money and resources..If game settings are not too rich, and game fits to play with turmoil, the main minus of turmoil is a risk not to have enough income on early stage, when you NEED guaranteed income to buy commanders and sacreds each turn.
Ideally you should play test game to see what you can get and what Sloth you can afford.
As for money - it's a question of game settings, early heavy taxation of capital, and, of course, look if the nation you choose
As for domstr, I take 2-6 domstr. 2 is rarely, it's risky, and needs very heavy justification. But alive pretender compensate your early risks somehow, generating dominion from 1st turn.
As for using rainbow pretenders for level 9 bless..If you have at least 1 point n the path you want to be lvl 9, I believe it has a sense.
As for research - you will almost never research in magic negative land. You dominion is weaker then your neigbors, so you will usually have access to at least Magic-1 lands. And dues to faster expansion you will have more lands, more capitals, more gem income and more money. They should compensate lack of magic scale even if you are not very lucky with finding good magic land in a place, where you can produce mages or where you can transport them to without sacrificing too many turns on movement. But even transporting your mages to magic+ land can be not so bad, getting to account that you will have your mages on the border with one of your neighbors, creating a threat and peace of mind for thought about defense. You will ALWAYS have access to Drain-1-2 (which means magic minus 1) lands, which is already doesn't sound so frightening as drain 3.
As for dom 6 for early rush - 6 is definitely enough for most nation for early rush (especially in games where settings are not rich). If you can rely on thugs with 1-2 sacred bodyguards, you can live with lower, even very low dominion. Don't forget about early usage of your mages - with researching pretender you have early access to body etherial, destruction, wind guide and other early spells which will change a lot for your wars.