Hi Alan...
I had one of the SE reflexion filters which worked ok but I sold mine in favour of rigging a mic up in a wardrobe full of clothes (😀) which I really think worked better for me.
When I had my garage converted into a room I use as a studio, I was able to pick up a bigger, framed, vocal booth pretty cheap which I’ve lined internally with heavy curtains and that’s brilliant. It also has the benefit that I can hide away in there whilst I’m screeching and fumbling around vocally. That’s the most important thing for me.
What I would say, though, is that your vocals are a real highlight of all your recordings...so I am wondering if you’ve identified a problem that needs addressing, or if you’re pondering dropping a reasonable £50-£100 on something that will improve the sound to a greater or lesser extent...
I suppose I’d sum up my ramblings by saying that I didn’t think that I got enough benefit from the filter I bought but they do absolutely help. I was perhaps just too cloth-eared to appreciate the slight improvement or too cynical to consider it worthwhile.