I've been wanting to get one of the VAL INS units for a while now. How did you like it? Unfortunately, there are several other items that are further up the list at the moment.
I have an INS-429 and like it a lot. It is similar to the 422, but has two knobs for entering frequencies and radials, instead of the switches. I don't know what other differences are. Val seems to make good products.
I do not have the antenna. It was connected to a duplex box for the GS and VOR and the MB was hooked to a separate antenna. It came brand new out of the box and was not used previous to our use.