I have had a Wanhao Duplicator 4S for three years now and it still performs well. It is difficult to get 3D prints to dimensional accuracy due to spread. Sometimes the only way is guesstimation. For general purpose though, it is OK.

The main problem, I have found, is bed adhesion. It is a bit of a titser when a corner lifts. I have tried different bed temperatures and bed substrates (Kapton tape, masking tape, ABS washes etc) The current one giving me some success is frosted glass with an ABS wash (thin solution of ABS in Methyl Ethyl Ketone or Acetone (Dimethyl ketone). I now run the bed at 110 degC for ABS and I don't print with anything else.

I bought the steel framed model for rigidity and I feel it was a wise decision. The second extruder has hardly been used, I have never seen much necessity for two colour prints.

I am about to rebuild the RH extruder as there is wear on the feed gear and the plastic frame has a pear shaped hole where the filament feeds, which makes it awkward to change filament.

I always print from SD cards as I can turn everything else off in my den and go to bed, leaving the machine chugging away (all night sometimes).

One last point :- Sam Courtenay, the Agent for Wanhao in UK is one of the most helpful people I know in 3D printing, sending me related parts, in case they were needed, when I only ordered and paid for the primary bit I needed.

Cheers,

Rob