Hi,
Brightest normal sized warm white LED lamp on the UK market that we've seen (and we've seen a lot) is the Megaman 141751 7w at 550 lumens (verified lumen level).
Hope that helps
As always its horses for courses with these things. The Redring Powerstream should only really be used for hand basins and mixer showers but there are always exceptions to the rule where people have had success using a Powerstream for a bath or kitchen sink etc. There's a few examples here...
Scolmore do a flat plate range in black nickel that take the interchangeable switches, but I don't think its screwless.
I think if you want all that in one package you'll need either Focus SB or GET - but it'll cost ya :)