You'd need 2x viparspectras I think to cover a 40 breeder, and then would have a lot of light spillage.
I have viparspectras (2x 165w) and while they grow coral (and look good to my eye) they have poor spread with significant hot/cold spots that weren't obvious to me until I measured. With a par meter it wasn't bad to dial in since the hanging kit is great for optimizing mounting height and you can also fine tune intensity but I expect without the par meter you'd have areas with either way too much or way too little par. Actually probably both - they need to be mounted rather high off the water or you get spotlights and your coral can easily be burned or light-deprived.
Given that they are a relatively cheap option and most ppl don't have par meters I'm recommending you borrow a par meter. That said they are pretty slick, the remote works well, and they have sufficient controllability without the heavy price tag.
I think they have too much white light, but that's a personal pref thing.