The only concern in using an N scale decoder in HO is the current draw of the loco. Generally the decoders I'm familiar with are rated at 1.5 amps for HO, 1 amp for N. The only HO locos I can think of that would draw an amp would be old old Athearns and Hobbytowns. So usually the N scale decoder should present no problem. Do check the draw of your loco and the spec of the decoder first. The N scale decoders I have used did not have connectors, I hard wird them. Hope this helps.
Gary
