Typically a 4 blade will get you out of the hole faster, stay on plane at a lower RPM, handle better, and if the engine is lifted on the transom, typically a 4 blade will allow a higher mounting height before it blows out.
The extra blade DOES however increase drag, therefore reduces speed...just a little. I noticed just less than 1 mph difference but it's worth it! (25 HP 4 stroke yammie)
I also run a river that will have 200-400 yard runs of 10-20 foot deep water, then immediately it goes from 20 feet to rocks with less than 12" of water (have to get out & pull the boat over if the water is low like it was last weekend). There are a couple shoals that will work your patience for sure. The 4 blade does well in situations like that where you want to run as shallow as possible yet be able to jump up on plane quickly.
I run a Solas aluminum. They also make them in SS, and the SS 4 blade props are a bit faster than the aluminum ones are.
Reverse was almost identical between the 3 and 4 blade.
Sometimes I wish there were a "high five" for little motors. Ran a high five on my old bass boat with the little 90 HP motor...that was an awesome prop. Reverse sucked but it wasn't a big deal. You get used to it.
Ideally when switching from 3 blades to 4, you'll want to drop 1" pitch because of the extra blade's drag. That is a rule of thumb. On my 25 I had to go down from a 3 blade 12" to a 4 blade 10" to get the RPM back...but mph only dropped just a tick.
As mentioned, it's also possible to run the engine higher on the transom, so if you can do that, it'll help there too. Watch the water pressure or pee hole though.