HEDP,
A Seahawk is quite a different beast to a Blackhawk. It's not a Blackhawk painted grey as a lot of people believe. It's deck handling qualities aren't even close to the capabilities of the the Lynx. It is more complicated to recover to the deck and has lower deck limits. In my experience of operating alongside Australian, US and Spanish Seahawks they also seem to be a lot less serviceable than the Lynx which is hard to believe I know! The Seahawk is also primarily an ASW helo with an ASuW capability whereas Lynx is an ASuW helo with an ASW capability (albeit a fairly gash one, but who wants to do ASW anyway?
).
Whilst I agree that the FLynx is a poor choice for the Army anything less than FLynx would not suit the RN.