I clean house rain gutters here in South Texas by hand.
I tried the pressure washing attachments and had to rinse off the house when done besides the mess out in the manicured lawns/gardens, the homeowners don't like that junk in their well-taken care of yards/gardens.
I tried the leaf blowers but when you have little trees/gardens in the rain gutters, the leaf blowers will not blow that stuff out, especially when there are root systems from the plants holding all the leaves and roof granules/dirt together in huge sections.
A strong shop vac will not work on those gardens also, if it had enough suction, it would only pull a small section down so you would have to lower the vacuum pole down and pull off that section of garden or shove it into the hose then do another small section, section by section. I have a Nikro dual head vacuum and with 2" hose, that is what happened to me, the vacuum was strong enough but you need a 3" or 4" hose all the way to the container so the stuff would not clog up the hose and my system is not designed that way. O Well.
I clean house rain gutters by hand so that I get everything out. I do use those gutter tools with the extension poles but the problem is that where the gutter attaches to the house, probably every 4' to 6', you have that nail that goes through the gutter so the tools will not work good trying to go under the nails or high above them at angles unless you have an angle adapter tool which they do work good.
When you are cleaning out the gardens/little trees, it is easier to get closer to those areas and have more leverage for digging out the gutters.
I charge by the house with 2nd story houses more since it is a lot more dangerous and more climbing.
I have had rain gutters 1/2 way filled with roof granules, have had them full all the way around the house with leaves/plants that turned into a big clod of dirt. That will not pressure wash out without making a huge mess and then having to clean the yard and wash the house is not worth it to me, I will just clean out the gutters by hand.
Downspouts, I wish there was a plumber snake that would clean out the downspouts but most of those snakes have a spring on the end and the snake itself is not physically strong enough to dig/drill through a whole downspout full of leaves/dirt/roof granules without twisting/coiling when it hits a hard spot and cannot drill through it.
You would need a professional snake with the cutter blades on them but then you have the possibility of cutting through the downspout and have to replace it. I just take them apart and clean out the obstructions then put them back up, it does not take too long but the 2nd story downspouts are harder to remove and clean as they are a lot longer but can be done.
I am thinking about trying a 1/4" pressure hose with a zero degree nozzle at the end to put into the downspout to blast through the muck and maybe will work to clear out the obstruction. The problem is that when the obstruction is at the top working down, you will get blasted with the muck unless you have a big towel over the downspout where you are putting the hose down into, sometimes the downspout is clogged up at the top so the hose will not go down much at all if any until enough is blasted through. I tried with a 3/8" hose but the coupler at the end of the hose made it harder to work with. Have a solution for that one now, just have to get the 1/4" hose, probably 50' will handle all 2 story houses and some commercial locations.
Good luck.