I did my old Warmbac in the washer once, and I am sure it was less waterproof - reasoning - the ploymide / PU coating inside cracked really badly.
Warmbacs are a right pain to clean, mud gets ingrained in the 'course' fiber of the material.
Last years summer I splashed out for a PVC Meander, great suit and so much more waterproof and so easy to clean. Down side, I cannot see it lasting as long as the Warmbac.
Mr Mike www.mineexplorer.org.uk