It's still on the hand of my friend, we didn't have time to do the transaction, yet.
I shall test it for white light with my APM Herschel Wedge, and if the color is more than desirable, I guess a simple color filter, like a green one is going to heal most of it. And I guess the performance of it with a Baader CaK should be outstanding.
If that's the case, this would be useful for H-alpha as well. Of course, I shall test it with my Cheapy-ERF + PST etalon module combination, I guess we will need a barlow both to reach focus, and to get slower focal ratio for the PST etalon module. Finally, if it works out, but not so well due to the internal reflection issue, I shall go ahead and buy a 75mm Lunt's filter. With 75mm, and at 820mm focal length, it's going to be powerful enough.
Of course, if it works with the Cheapy-ERF, that would be the best in terms of resolution and also the cost.
And it will work as a wide field deep sky instrument, it just won't work for planets and the moon.