Hello Paul
Here at Papworth we have 9 Servo i ventilators and 4 Galileo Ventilators. The Servos are used heavily in our CCU and the Galileos are less heavily used in the Chest Unit.
I have found the Servos to be extremely reliable and cost effective in both maintenance and repair. The only problem is the need to replace the battery modules every 3 years at a cost of about £200 each. Maquet recommend fitting each ventilator with 2 battery modules.
The Galileos have caused no problems and I have only seen them when they are due servicing. However the service procedure is rather long winded and requires special tools.
Hope this information is of help.
Chris