I said I would test this a while back but I had put it aside waiting to finish a build or two.
I did a brief post test which was fine.

I contacted Imagination Technologies and although I did get through to someone, they didn't get back to me (understandable).
I've never seen a Neon 250 with TV-Out or any literature but had read an arcade version existed.

Today I found this article in PCPowerplay 1999, the only image of an R-Cade Vision 250 I have seen and it is similar to this card.
Apparently supporting 15, 25 and 31KHz. Which now makes sense as there are two dip switches like an EGA card.
It also mentions a daughter master board to attach for controllers but this was not in the lot I purchased.

https://archive.org/details/PCPowerplay-035-1 … de/2up?q=r-cade

Background:

I picked this up from eBay US over a year ago after envying the few neon 250s on this forum. I thought I would never own one.
It was in a scrap pile, could not believe my luck. I used the search term "NEC AGP" in blind hope. (It hasn't worked twice)
Realizing now it was probably a prototype for an arcade system I tried to check my ebay purchase history for the original seller but it's gone sadly.