Diaphragm pumps do work well for honey, at lower pump rate needs. They also take through solids and debris (wax, bees, etc), crystallized globs, etc. The are also of light and portable construction. Obviously the colder and lower MC the honey is, the thicker it is and thus the slower the pump function. The nice thing about DPs is they do not cavitate nor will they whip the honey. Some DPs have built in non-stall auto-switching feature. Those non-stall ones you do NOT want for honey. Else when the honey gets thick the pump will be in constant auto-unstall mode and not pump at all.
Depending on unit size, air operated diaphragm pumps can use up alot of compressed air volume. That is OK if your shop is setup and can supply it. Little porta-compressors will have a tough time and can barely keep a 1/2inch pump going. There is an electric DP pump option (no air), which is very pricey. I hope to try one of those eventually.
With those caveats - the DP is otherwise a nice clean and simple option for pumping needs of high viscosity and low volume rate.
A step up in reliability would be low speed big bore plunger pump. (sludge pump)