Fr. Maximagus, I think they are both effective, but take different routes.
A small preamble.
I really hate making what sound like truth claims, so take these as what they are: me attempting to describe my experiences, rather than any final word on the practices themselves, or the ultimate nature of reality.
Expanding on my thoughts from the 'What New Age gets right' thread:
OK. I got good at magic (meaning sorcery) by surviving , and helping those who I did sorcery for, to survive the many psychopaths found among the corporate armies of the undead, defeating numerous nazghul , and a legit balrog or two. The only comparable situation I can think to perfect one's Arte might be in being a service magician (brujo, sorcerer, boko) on staff for a drug cartel, or maybe in prison. Fighting evil with evil, fire with fire.
For those who have not worked with them, demons (daimons, imho) often work like intelligent “spells”. Whereas, as far as I can tell, New Thought simply... sort of shifts everything at once one day when you're not looking. It's cool and honestly shocks the fuck out of me more.
It's a little hard to communicate the difference without an example from IRL.
Around 2005, my girlfriend at the time worked in a hostile corporate environment, and was being maliciously attacked by one of her office frenemies to drive her out. To protect her, I used it as an opportunity to use a classic spiritual subjugation working. I gave the demon instructions to make them "sit down" and continue until the danger was eliminated.
At first it manifested effects in the target emotionally, such as self-doubt. But being a psychopath, I suspect, they shrugged that emotional attack off. Per my original charge to the demon, which one of the Legion I do not remember, they then escalated the attack so the psycho was driven to distraction by petty accidents, so much so they were often out of the office. Eventually it made them very sick so they left. Problem solved.
If my girlfriend's attacker had been a person with normal emotions they would have just been made to sit down, and take a breather, and been under my thumb. In my view this is the problem with demons. They are relentless and inclined to overkill. Now I tend to only use them when you need an extreme push at a specific place. A whack with a hammer. I tool very useful to have in one's kit.
With New Thought the effect is like “poof” – suddenly reality shifts and it's just not a problem anymore. Like, don't whack the car… just get a new car.
And I ain't no New Thought master, but it seems like effects in a sort of generalized way, closer to archangels. Good stuff!
But for a while it sort of weirded me out far more than Lovecraftian critters showing up in my living room to do some business.