Aesir:
It is important to land vertically with as little or no forward motion as possible if the floats are released in flight. I have been told that they can be ripped of if landing with forward airspeed as they are designed to lift the helicopter up and not act as water brakes
This is a myth that cannot go uncommented; the following is taken verbatim from AC 29.801 - look particularly at paragraph (C):
b. Procedures. The following guidance criteria has been derived from past FAA/AUTHORITY certification policy and experience. Demonstration of compliance to other criteria may produce acceptable results if adequately justified by rational analysis. Model tests of the appropriate ditching configuration may be conducted to demonstrate satisfactory water entry and flotation and trim characteristics where satisfactory correlation between model testing and flight testing has been established. Model tests and other data from rotorcraft of similar configurations may be used to satisfy the ditching requirements where appropriate.
(1) Water entry.
(i) Tests should be conducted to establish procedures and techniques to be used for water entry. These tests should include determination of optimum pitch attitude and forward velocity for ditching in a calm sea as well as entry procedures for the highest sea state to be demonstrated (e.g., the recommended part of the wave on which to land). Procedures for all engines operating, one engine inoperative, and all engines inoperative conditions should be established. However, only the procedures for the most critical condition (usually all engines inoperative) need to be verified by water entry tests.
(ii) The ditching structural design consideration should be based on water impact with a rotor lift of not more than two-thirds of the maximum design weight acting through the center of gravity under the following conditions:
(A) For entry into a calm sea--
(1) The optimum pitch attitude as determined in 337(b)(1)(i) with consideration for pitch attitude variations that would reasonably be expected to occur in service;
(2) Forward speeds from zero up to the speed defining the knee of the height-velocity (HV) diagram;
(3) Vertical descent velocity of 5 feet per second; and
(4) Yaw attitudes up to 15°.
(B) For entry into the maximum demonstrated sea state--
(1) The optimum pitch attitude and entry procedure as established in
(2) The forward speed defined by the knee of the HV diagram reduced by the wind speed associated with each applicable sea state;
(3) Vertical descent velocity of 5 feet per second; and
(4) Yaw attitudes up to 15°.
(C) The float system attachment hardware should be shown to be structurally adequate to withstand water loads during water entry when both deflated and stowed and fully inflated (unless in-flight inflation is prohibited). Water entry conditions should correspond to those established in paragraphs AC 29.801(b)(1)(ii)(A) and (B). The appropriate vertical loads and drag loads determined from water entry conditions (or as limited by flight manual procedures) should be addressed. The effects of the vertical loads and the drag loads may be considered separately for the analysis.
(D) Probable damage due to water impact to the airframe/hull should be considered during the water entry evaluations; i.e., failure of windows, doors, skins, panels, etc.
There are separate critieria for helicopters which have not been certificated for ditching and are equipped with emergency floats.