That Scorpion at £600 is a bargain if its all ok. Performance wise its a massive leap from the Steempro.
Maintenance wise its good and bad. The vac motors are just held in place by a large hose clip - easy to remove, but the access and room can be a pain. The 2 front vac motors can be accessed by just taking the front dirty tank off which is easy - undo 4 bolts underneath the tank, then just pull the vac hoses off the tank underneath and you are done. The water pump and back motor is more fiddly - the back clean tank has to come off which has the water hoses fitted on and is more involved. Its not really difficult - just a lot more time consuming than the better thought out designs like the Airflex - the way it opens up and gives access to everything is really good for maintenance.
The motors and pumps/spares are freely available so you wouldnt have to use Solutions to buy the bits if you didnt want to.
The Scorpion i had was very reliable for vac motors. The most frustrating thing were the toggle switches at the front to turn on the vacs and pump. They are a toggle switch you can find in Maplins and just arent hardy enough - it was really frustrating loosing a vac motor on a job - not because the vac had gone but because the silly toggle switch on the front had!