I have a set of DB5’s on my bike currently; they are under powered (180/160mm rotors) and have a horrible spongy feel.
Plan A is to:
keep the DB5’s upgrade the rotor sizes, new pads and a re-bled this will cost about £110
Plan B is to:
fit the SLX’s, this will require a mismatch mount, new reverb lever and a bled to get hose through frame (possibly new hose too) this will cost about £120
which would you do? never been amazed by the DB5’s but loved the SLX’s when they were on my bike about a year ago. I have no idea whether they will need a bleed now though.