Re: series drogue or para anchor?
Having used both in weather that actually requires it, over 60 knots in most cases, I would never use a sea anchor again. I was constantly worried about damaging my rudder as mentioned above.
Towing a drogue also has it's own problems. Though I have not had this happen to me, I have met people who have had their drogues end up in their rigging, which must be a real pain in the a**.
Alternately, I have had a drogue slow me to the point that I was constantly being pooped, filling the cockpit frequently. In the end, the only solution was to cut the thing free and allow the boat to sail unrestricted under bare poles. It is a tremendous amount of work to steer in those conditions, at times surfing across the face of the waves at ridiculous speeds, then pointing the bow directly down wind to allow the white water to pass underneath as it overtakes you.
But if I can keep the boat under control, I feel I am much safer than hampering her with a drogue, so I no longer keep either aboard. Should I ever (Neptune forbid) get into a situation where I feel I should drag something to slow me down, I can see no reason why one or two of my 6 anchors with 30 or so feet of chain, on a long anchor rode, would not do the trick.
"Any idiot can make a boat go; it takes a sailor to stop one." Spike Africa aboard the schooner Wanderer in Sausalito, Ca. 1964.