I would agree with @slooty that the ability to scale WFE is very enticing, however most of the smaller labs which are in-house to a vertically integrated company, versus toll processors and large scale operations or commodity refinement such as hemp, are going to do fine with SPD or SBD.
IMO another pro to WFE is that often the systems are much more modular, although the SPD sector is getting better at this, and allow for a little more plug and play. Although I would have to say this is a bit more true of stainless systems where using KF/NPT/JIC fittings without extra adapters makes them optimal. We could probably start a whole thread on SS vs Glass, even just discussing their insulative and wetting pros/cons.
A con to WFE would be that they are often very time consuming to break down and clean, especially glass. Glass WFE bodies can be quite tedious and nerve wracking to clean, an ultrasonic cleaner and a good surfactant can help mitigate this.
I would say the lower overall residence time with WFE is a pro, especially with the ability to keep your feedstock in a separate addition funnel or feedtank at an isolated and lower temperature, while also having the ability to directly change and control your residence time on the evaporator with your wiper.
When referring to the “pass” on a WFE are we talking passes per distillation at one set of parameters, or overall distillations at a variety of parameters? WFE can be adapted to a recirculating system for your raffinate allowing continuous passes on the evaporator without having to reload the feed tanks manually.
Of course as mentioned before, the cost of the WFE dosing system is the inability to perform reactions the way SPD can, although this may not matter if your operation is only focused on D9THC/CBD refinement.