Formability is not necessarily compromised by upgrading the steel in a design.

To maximise the potential benefits, it is generally advisable to design using the high strength material rather than simply modifying an established design.

Forming of stronger material can require more power; this is partially compensated for by the thinner gauge. Generally it is possible to process an upgraded material on existing equipment.
 
The Sheet Steel Forming Handbook from SSAB Swedish Steel gives a wide range of data on the various forming processes to enable effective forming of high strength materials. It is very important to set tooling correctly. 

Many high strength grades still exhibit excellent drawability, enabling quite complex forms to be produced in a material that will allow substantial weight savings. 

Detailed advice and FEA analysis are available from SSAB Swedish Steel if required.