A look through the U.S. Terps document (N8260.3E) states this:
The minimum PT distance is 10 NM when CAT B, C, or D minimums are authorized. Decrease this distance to 5 NM where only CAT A aircraft or helicopters are to be operating, and increase to 15 NM to accommodate operational requirements, or as specified in paragraph 2-4-5.d. No extension of the PT is permitted without a PFAF. When a PT is authorized for use by approach CAT E aircraft, use a 15-NM PT distance. (page 2-23) (section 2-4-5)
2-1-7. Approach Categories. Aircraft performance differences have an effect on the airspace and visibility needed to perform certain maneuvers. Because of these differences, aircraft manufacturer/operational directives assign an alphabetical category to each aircraft (see 14 CFR Part 97). The categories used and referenced throughout this order are CAT A, B, C, D, and E. The authorized CAT must be used to determine OEAs [obstacle evaluation area] for circling and missed approaches and used to establish landing minimums. (page 2-5) (section 2-1-7)
My opinion is simply this: If there is a required procedure turn, hold-in-lieu-procedure-turn (HILPT) or DME arc, these are all based on the category aircraft approved for the approach. I would fly these segments at a speed lower than the maximum authorized category on the approach.
Once I cross the PFAF or FAF, I will fly a speed that does not exceed the category I am using for that approach. For a stabilized approach, I will be at my VREF speed by 1000' AGL in IMC or 500' AGL in VMC and that will ensure I am in the category I need for the landing mins, circle and missed approach.
I found nothing in the TERPS that requires you to fly at VREF at the PFAF or FAF. You could cross at 200 KIAS if you wanted to or told to by ATC. You could slow down to VREF by minimums and be in the correct category... I suppose. I mentioned a stabilized approach for a reason, a great landing is preceded by a great stabilized approach. Am I willing to risk becoming unstabilized to fly faster and slow down by the (M)DA? I am not personally willing to do that... so I go with my previous statement. 1000' AGL in IMC or 500' AGL in VMC.