GKN Loebro is the OE manufacturer, I used a pair of GKN Loebro boots in their box and saved 28 dollars compared to the OE Genuine BMW boots in a BMW box (40 dollars for Genuine vs. 12 dollars for GKN Loebro)

I would stick to GKN Loebro for inner and outer boots, although the inner boots do not fail as much as the outers, to be honest I would leave the inner boots be unless you have one leaking. They typically should last a few years or maybe 100k or so miles, but tend to fail much sooner depending on driving conditions, doing a lot of tight turn driving, and environmental conditions which break down the rubber on the boot.

In South Africa I would imagine age, heat, and mileage can be a factor. If your X5 is a 2005 and has original boots on the outer CV axle, I would replace preventatively to avoid them failing on you

__________________
2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards