Unlike the stoves with a vertical flue the inserts aren't likely to accumulate much debris behind the cat. Also, I believe the bypass opens differently which could allow better access for cleaning from below. Seems to slide vs. tilt.Take the flame guard off and vacuum the cat (don't take it out unless you have a new piece of gasket).
I don't know how you could vacuum behind the cat in an insert (I take the pipe off and get in there, but with an insert you may have to go thru the hole in which the cast is located).
As to Jedi's question, looks fine. It's the right color.