Yes, it's lower price and it's probably good for basic or straight forward health issues!
Waiting time is pretty much same as any other - private or public.
BUT.....I reckon if you can afford it and know good trustworthy doctors who won't get you to do unnecessary tests or give you unnecessary medication (don't you hate those docs that would give you several different pills all colours of the rainbow just for a basic cold or flu, including antibiotics every time), then it may not be as money or time saving to go with cheaper clinics like FCU as you think.
I've found from experience that having full body check-ups at cheaper clinics, or those offering discounts, end up advising further unnecessary testing (more costs) and worry. I luckily avoided invasive costly further testing that FTU insisted I needed a few years back, by seeing a private specialist for a 2nd opinion.
I had a separate routine test by FTU once and they sent results (v personal details) days later in the post surprisingly on a piece of folded A4, taped on sides (I guess they are trying to save money by not using envelopes?).
I've preferred not to go to FTU since.
I'm not saying all pricier health clinics are more reliable than cheaper health clinics, but possibly may be good to be more cautious about the reliability of testing and advice. In complex cases with need of a second opinion or repeat testing, the cost could actually be higher than you anticipated.
So if you can afford it, choosing a "good" doctor at a clinic that has higher prices, can sometimes actually save you worry and money overall.