It really comes down to budget. If plan to have a huge turbo or have money able to spend on a costly manifold there's no harm in doing it, but its not essential.
Think someone had a serious fitment issue with walton lately.
I've got a cheaper xs power and never had any issues. The problem with the budget manifolds are the waste gate location being under the car. This is a right ball ache. I modified mine by rotating the waste gate outlet tubing to locate it in the engine bay now next to the turbo, but its just hassle to do that for most people. Benefit of costly manifolds they don't have this issue and its all there in the bay from the word go.
I also ported my manifold to make it nice inside. But at 600hp I've never had any exhaust flow issues and boost control has been consistent.
If you can afford a higher end manifold without impacting the project. Id go that route. If a manifold cracks. You can weld it. It's not a deal breaker. But rotating the waste gate outlet is for, sure hassle. And welding is highly unlikely. Some cheaper manifolds also report of not having a true flat mating surface on the head. I skimmed mine after rotating the WG outlet and adding bracing. But this was just a precaution, as it had been through some serious welding. Another step to ensure I had no issues, with an expensive one you shouldn't even have to worry about.
My only other niggle is due to the custom work I cant fit an exhaust cover on for heat shielding. Turbo is too close to the WG. Which was just an oversize during placement. As I didn't think about heat protection. Just something to keep in mind whatever route you go.
Having the wastegate under the car is not an issue. But if you have a problem. Suddenly it becomes a right pain.
For sub 800hp, a cheaper manifold and a few home improvements go a long way and save lots of tokens. If you just want a plug and play option and can afford a pretty one, I'd get one from whifbitz or srd. I've not felt there's any benefit using an over seas supplier. If there's an issue. It's a lot of money to faff around over.
I have a 6870 on order (which has taken nearly a fking year) and I intend to use one of the two suppliers above for that. Then I'll sell my beloved xs power.