The clear vs white background is afaik exactly that: if you like preshading or not. I worked more than once with Aviattic decals and I was always very happy when using them. They are thin, strong and stick well to the surface (important if you have to mask over them). On my last build I used a hair dryer to bring them down into the recesses and it worked really fine. There’s only one thing you have to be careful with: they need a flawless, glossy surface to avoid air bubbles under them. So a careful coat or two of future or whatever you use is essential. I frequently worked with huge decals (covering a whole lower wing...) and never had any problems. And if you use the „cookie“ decal sets, you even avoid cutting rib tapes, another huge advantage in my opinion.
I have no connections to Aviattic but being a satisfied customer, and I cannot phraise this stuff highly enough.
Andreas
P. S. There are critics out there who dislike the linnen effect on the decals , it is out of scale they say. I disagree with them and I love this effect of woven canvas.