Personally If i was in the market for adding some power to a d-series motor I would personally go with a super charger. ( i currently have a turbo on my b18c) and the reason for it is simple.
Most of the time people who are wanting to add a little speed to thier d series arent going to be willing to back it financially to properly turbo it. a super charger is a nice cheap and fairly reliable way to get some safe power out of the motor without killing it.
sure the cost of a jrsc or similar is abot the same as a standard turbo "kit" on the market but anyone who really knows... a turbo "kit" isnt a complete FI solution. atleast for doing it right. If you have and are willing to put the funds into the motor to properly turbo it then you should seriously consider a swap in order to really maximize the gains with a dohc motor. either way this is just my opinion and youre free to do what you like but atleast it gives you something to look at.