we too bought a system from them and have to say alex and kirsty have been very helpful in advice over the phone and getting parts to us quickly when we needed them.
the only thing i would say is we have found that their maxi system which is supposed to enable two men to work for up to 6 hrs, and includes a 650 ltr tank and a 300gpd r/o unit is not big enough, i know this is because we are using too much water, but this is because we are new to wfp and i feel that the advice given should have taken this into account, i am not knocking gardiner because they have helped us a lot, just trying to stop anyone making the same mistake we made. so make sure the system you get is going to enable you to work for a full day. we have found that the tank would not fill up over night, unless your pressure is very high indeed i.e. 60-70 psi at least it wont fill on my tap which is abou 35 psi even if left for 14 hrs, so we thern had to purchase a pump to help it along, then we found that a full tank wsnt enough for us to do a 6 hr day, but if we buy a bigger tank or an additional tank then the r/o wont produce enough water.
alex will be able to advise you better on these points but i think we would have been better advised to go for a 1000ltr tank and a bigger r/o unit.
i have to say though that their poles are great the microbore hose is excellent althought i would go for a bigger reel then the one they supply as it is only just big enough for 100m of microbore.
all in all their service is great.