I've sold more of the Dobinsons snorkels than anyone else, and I don't know where you heard that, but it isn't true. Material thickness is the same as the ARB.ARB- Its still a toss up as I've heard they're much more Durable than a Dobinson, but... "SaFaRi" on the side is just mega-cringey for me.
Dobinson: I've heard is weaker walled than ARB, no "SaFaRi" logo, but just concerned about the durability.