Are you talking about the use of these machines as carpet cleaning tools ie granules/powder, or as an agitator tool.
As agitator tools they both do a good job in that they distribute the releasing fluid around the fibre and lift the pile. I understand the Flexii 5 (or Carpet Gard) is designed for "wet" use ie sealed bearings and electrics, whilst he Envirodry is not.
So on that basis the Flexi5 wins.
As carpet cleaning tools the Flexi5 has the built vacuum pod built into the unit. The brushes and vac can be used to dry vac the carpet at the outset, then just the brushes to agitate the sponges, then the brushes and vac to collect the dirty sponges when dry.
The Envirodry is just the brushes so you need a seperate vac unit ie Sebo.
So for this purpose the Flexi5 wins again.
Its just the cost issue - the Envirodry about £1100, the Flexi5 about £1800 - so £700 for a vac pod.....hmmmm.
I also have some design issues with the Flexi5 - or in my case the Carpet Gard.
Within 3 weeks or so of getting mine (second hand) a toothed belt stripped some teeth. To change that belt was a marathon job. Obviously 2nd time round I will be quicker - but not looking forward to 2nd time around.
There needs to be some sort of self tensioner on the drive belts as there tension is critical - too slack you strip teeth, too tight you ruin a bearing.
The flexible vac hose pipe connecting the vac pod to the man body is at a very tight angle when in use and easily split - hence mine is taped up.
Also. there is a micro switch (or 2) that a) prevents the unit to operate when the handle is in a vertical position b) prevents the unit operating unless the handle is in a certain direction (difficult to explain really.
Would prefer if the unit was to sit in a tray like the Envirodry or on a trolley like the Host.
Overall, as most carpet cleaners are using this design of machine as a agitaor the Envirodry wins on the basis of its price and functionality, but the Flexi5 does have the benefit of water tightness - but at a price.
You pays your money and make your choice.