Except as otherwise provided elsewhere in these rules, on their effective date:

(a) Any acts done before the effective date in any proceedings then pending or any action taken in any proceeding pending under rules of procedure in effect prior to the effective date of these rules and any constitutional right are not impaired by these rules.

(b) These rules also apply to any proceedings in court then pending or thereafter commenced regardless of when the proceedings were commenced, except to the extent that in the opinion of the court, the former procedure should continue to be made applicable in a particular case in the interest of justice or because of infeasibility of application of the procedures of these rules.