I think these days, you will find all the 3 stage converters to be around the same quality and work similar and such.Has anyonr had any experience with a PowerMax-50 convertor/charger, it is a 3 stage charger. The good/bad/ugly please.
What you said...For the money the pedestrian converters targeted to the RV market are generally OK and way better than the single stage analog and SMPS units of yore. If you want truly supported and user configurable equipment look at marine grade stuff for 4-8X the cost.
The WFCO products, in my limited experience and what I have read, are JUNK. I pulled out a WFCO 9845 from my trailer. It was mounted in a special made tray WFCO sells with it to replace the converter in a Parallax panel. I think it was fairly new, not sure, but after monitoring voltages for a number of days, I found it does not cycle thru the stages as it is supposed to, never dropping to the lowest voltage. I removed it and ditched it in favor of a Progressive PD 4645 and it (on the same battery) cycles very nicely thru the stages as the mfg graph shows it should. It has the advantage of a new DC fuse panel with the LED and push button to force the converter to different stages manually. This is useful if you want to top a battery using a generator and have limited time to do so and want to force it to bulk charge 14.6v to get it charged faster than the lower voltages it might automatically select.Yeap, no support and an utterly disposable product. That's a big chunk of the low price. The rest is cheap electronics, which yield a decent level of function and service life at low cost. The Powermax seems to have the usual features of a modern 3-stage charger.
A Progressive Dynamic 9260 is almost 2x the price. The WFCO 9855 is only about $20 more than the Powermax 55, though, and has a well-known brand name behind it. Your call.