Im going to throw a spanner in the works here and say: Why not a bulkier P&S like a G12 or newer G1X?
Yes I realise you cant change lens and the like, but it seems they can still perform the photography you want to achieve.
I myself purchased a G12 last year as I wanted to manually change settings, without the actual need to change lens'. I however also purchased a lensmate quick change adapter so that I could use the 52mm filters I had from my old p&s, and with the bonus of the adapter, I can use macro filters if need be
