I carry more than one anchor - I've got 3.
The 10kg Bruce (main anchor for coding), the 10m of 8mm chain (I think) and 30m of 12mm rope is soooo bloody heavy, it is a real pain in the arse. It's rigged ready to go, and was used once, but for for the last 18 months, has been doing sterling service as ballast in the anchor locker.
The 6kg Grapnel (secondary anchor or kedge for coding), the 10m of 6mm chain and the 30m of 10mm rope is still heavy but easier to handle than No 1 above. I use it if there is a swell or stiff breeze.
But, when I got my tender, I got a free 3.5kg grapnel, 30m of 8mm rope, and had some 5mm chain lying around. It's fantastic, has held whenever I've used it (in light conditions) - and it is easy to recover.
HOWEVER - I don't leave the RIB on the anchor unattended - would rather pick up a mooring. If I was leaving it anywhere, I'd use the big one, and put up with the back breaking haul the next morning.
Oh, and I always tie it through the painter so the D-ring takes the strain, and so that the tube doesn't get rubbing damage.