I'm certainly a proponent of shop dehumidification. However, the jobs of cooling (A/C) and dehumidification are best left to dedicated devices UNLESS you intend to run your shop A/C 24x7 AND are willing to put up with high/uncontrolled humidity during periods where it is too cool for the A/C to run enough to adequately dehumidify the shop -- hence my preference for dedicated devices.
With separate devices you can leave the dehumidifier set at a specific humidity and leave it to run 24x7 regardless of season. It will keep the shop at a stable humidity and reduce unwanted wood movement and keep your wood stock (at least that portion within your shop) at stable moisture content. If you dehumidify your entire shop, you will also notice a near immediate benefit in the form of greatly reduce rust and corrosion. I used to have to polish my cast iron surfaces almost monthly, with a dehumidifier it is more like every 1-2 years that I polish everything. I keep my shop at around 40%RH for maximum comfort, however any setting between 40-50%RH will greatly reduce rusting and maintain optimal moisture content levels in your stored wood.
However, when spray finishing you will have to turn off the dehumidifier (and A/C) to avoid drawing in any overspray (and possibly combustible fumes). However, if you were using proper (fan-forced) ventilation then they can be powered back on just as soon as you finish spraying. For brush-on applications they can be left running during the paint/finish application (provided any combustible fumes are ventilated). Once powered back on they will begin stabilizing the temperature (A/C or heat) and dehumidifying the work area.
You will want to opt for a large/high-capacity dehumidifier (50-70 liters/day) both for their improved efficiency (the larger units are much more efficient than the smaller units) but also so that the dehumidifier has the capacity to pull down the humidity as quickly as possible. Your energy savings over the course of a couple years will more than pay for the difference in cost between these larger units and the smaller/cheaper 25-pint/day units. If you don't wish to empty the dehumidifier's bucket up to several times each day, then you will either want to attach a drain hose and direct it towards a gravity-fed drainage point OR you can use an external pump that can accept the collected moisture in a temporary reservoir and then periodically purge the reservoir (under pressure) which, in my case, means up and out a window since I have no handy drain (in recent years Lowes has carried the pump accessory).
