Hi Dudek,
Microbore is really one of the best things that has happened to WFP. We have been using it now for 5 years and would really never consider using anything else.
The two things that really matter when using a WFP system are the flow rate of the pump (not the pressure as this just tells the pump when to switch off) and the flow rate from the brush head.
The main benefit of microbore is that it is easier to use, reel up, it doesn't get caught up as much, doesn't kink as much, is much lighter and you can fit twice as much on the hose reel.
A side benefit that we discovered when we started using it is that helps control the flow rate. The flow rate from a pump can be anywhere from 4-8 litres per minute, which is actually too much for general use. Standard 1/2" hose will slow this up somewhat, but microbore will restrict this even further due to the drag factor from the inner sidewalls of the hose. The other thing that affects flow rate is the size of jets that you choose on the brush. We have found over the years that 2x 2mm jets suit WFP purposes well. All of these will reduce the flow rate to about 1.5-1.8 litres per minute from the brush head if you are using 100m of microbore.
The above flow rate is about spot on for the average WFP'er.