Digitrax DH126D and SDH166D

Duff & Polly M

I currently have a couple of locomotives with Digitrax DH126D decoders.  I am not particularly interested in full sound, but would like to consider at least a bell or horn/whistle.  I notice the Digitrax SDH166D decoder might be a solution.  I will need to be creative with the speaker.  But first I would like to know how compatible are the two decoders?  The documentation suggests to me that I could unplug the DH126 and plug the SDH166 in its place, at least for motor and light operation.
Is the any experience with this?
Thank you.