My final gathering result. Irrad estimation radius is 0.2 which is quite low and causes some noise. Other parameters are as below. Took 32 Mins on 1 thread.

Indirect-only lighting with photon and caustics maps. 1M photons, 500K caustic photons, 512 max. photons used for irradiance estimation, radius=2, ellipticity=0.33. 23 minutes on 1 Thread.

Direct+Indirect lighting Estimation with photon map only. Same parameters as for Indirect-only estimate.

Estimating indirect-only lighting with photon map. 1M total photons, 512 max. for irradiance estimation [filter radius=1.5, ellipticity=0.5]. Took 6mins on 1 thread.

Estimating Direct+Indirect Lighting with same parameters as below.

Estimating Direct Lighting with Photon Mapping: 5M Photons, using 256 max. photons per irradiance estimation with radius=0.5 and ellipticity=0.2. 5 minutes on 1 thread.

I think this is close, but too dark to say anything more.

First attempt at estimating direct lighting with photon mapping [reflections, refractions are regular glossy]. Definitely wrong, but looks oddly satisfying. 10M photons. Took 3minutes on 1 Thread. Not doing Caustics yet.