Personally, I think that GA calls to Solent should go something like;
I disagree.
I suspect the reason that Solent might like to provide an FIS (which, without a radar service, in reality means nothing more TO THE PILOT than two-way radio contact) is that a lot of casual VFR pilots go very close to their CAS. Especially when going just below the 2000ft bit N of IOW. Obviously Solent can see the a/c on radar which is handy in case the pilot gets too close to something and can be called up.
The absence of an RIS means the controller gets to eat his cake (he gets the radar picture, plus 2-way radio contact which he uses only if he needs to) and gets to keep it (no need to provide a traffic service, or any other service really) to the pilot.
It MUST be better for Solent to have 2-way radio contact with VFR traffic passing so close to Southampton traffic, than to have them talking to say Goodwood (who cannot provide any useful service, beyond "three aircraft known in the area").