Jon.
We do gutter clearing,
We get away with £40 per side or £60 for back and front on clearing gutters or £100 for all wfpoled the exterior of gutters and soffits as well as vacuumed out.
Advertise it on your collection slips and you will be surprised on how many customers want it done, then get them to have it as a rolling 6monthly or yearly clean of gutters. I only have 800 domestic customers now but out of those we generally get 20/30 odd gutter cleans a month and then i put them on rolling 6 month and yearly cleans to keep them clear. Most customers go for this. As for being worth doing,, yes 100 percent, best day doing gutters by myself was £840 due to a lot of walkups but on a Average you will hit £600 for a day of gutters providing you book them all for a certain date of the month to do or tell them when weather is wet. It does feel great when so much can be earnt from being out in the rain.
Only been doing gutter cleans myself for 6 months but can say its defo worth it especially with the amount of customers you have you should realy smash it.
I do a lot of commercial buildings with the vac and that is also a great earner and gets you further in the door when giving quotes being able to offer both windows and gutters.