Boblee,
There are 4 bolts; each of them has enough breaking strenght to lift the free of the water, with lots of safety margin to spare, if the deck hardware would not be ripped out in the lift.
No worries
Obelix
Sorry wasn't the actual tensile strength that worried me me more the weakness of having nuts and bolts in so many varying conditions especially the jigging, hot, cold, wetting and drying etc and then relying on it but am sure if done up to the right tensions they will be ok and if checked regularly but IMHO something I personally wouldn't be happy with I would have to weld it.
As for lifting the anchors the Sarca has a slide for the attacment to move to the rear and the Sarca has a fixing point for a line to be attached to the rear, I have used the Sarca more inadvertently than on purpose (driving over anchor) but never the Rocna line attachment, both work well in sand weeds and rocks but a slippery hard bottom can cause difficulties as with any anchor.
The most important thing is to set your anchor correctly even the Sarca and Rocna (Mantus) easy set types can get a false set and it is wise to prove it by pulling with the motor if neccesarry for peace of mind on a long stay or leaving the boat unattended.
A change of tide or wind can also cause problems if the anchor won't reset easily.
When I did carry a danforth type did find it was good for setting an aft beach anchor when beaching on sand but the others just do it better anyway.