ISN has been having an internal conversation about backpack sprayers, so I thought I'd share it here. One partner expressed continuing issues with Solo sprayers, culminating in 2 brand-new sprayers arriving in non-working order, and asked about other options. Here is what partners have shared as other options in no particular order (both are more expensive than Solo, somewhere around $120-150):
Stihl backpack sprayers, which don't have the leaking problems and have broken less frequently; some models have plastic components that may break with time
Jacto backpack sprayers were recently recommended as very reliable with mostly metal parts
Of course, this isn't an endorsement of any products, just sharing experiences.