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The original D jet pumps used by VW in 1969 were roller vane ( 5 or 6 rollers ) and were very noisy, the looked more or less like the 999 pump except all hose fittings were on the head end ( early had 3 , later had 2 , the switch occurred when they went to an internal bypass rather than a hose loop ) I'd expect the 999 pump to be roller since the pump head is retained by 4 screws. ( see "old" pic )
The other brands turbine pumps I've taken apart use 2 turbines stacked together, I don't think there is enough room in the 999 head for that.
Newer crimped pumps ( 1997 C280 and E320 ) look like the "new" pic. I've taken two of these pumps apart and found them to be twin rotary screw. ( Look up a twin rotary screw air compressor on the basic layout ) These are virtually pulse free.
It would be good practice for a turbine to have a relief valve to protect the motor when the filter is clogged, I can't say if all have or not.
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