I used to use the SIS gels until the price went up significantly over the past few years, also it seemed the UK site was originally shipping locally in AUS but now ships from UK, and now there’s a separate AUS-based site which seemed to charge more/have less variety.
I now shop at the local supermarket for the ‘Winners’ brand gels which unfortunately are not isotonic like the SIS gels so I need to remember to have sufficient water on hand.
I’ve used the SIS Beta Fuel a few times for longer Gran Fondo events, works great from a fuelling and energy perspective - however I have found repeatedly that the, ahem, “after effects” (and I’m not talking about the gut) are an issue for the next day or so - not sure if this is just needing to “train” the digestive system to get used to the higher level of carbs or whether I’m just unable to tolerate the mix of sugars 
I’ve yet to find a caffeine gel that tastes anything less than horrible - I love strong coffee but caffeinated gels just taste nasty.