I'm not siding with OnePlus, but the Z4/Z3+ has a waterproof metal/glass enclosure which may have exacerbated the overheating situation. The OnePlus 2 may not suffer a similar problem. There is currently another device in the market that uses the v2.1 chip, i.e. Xiaomi Mi Note Pro. A quick Google search will reveal that there was a complaint in China regarding overheating (
which was quckly picked up by tech sites) and claimed to be proof of v2.1 overheating. Xiaomi has since come out to clarify that the incident was an isolated incident and overheating on the Mi Note Pro is largely exaggerated. In fact, Xiaomi has applied for several patents that dealt with heat dissipation, which allowed the 810 to run without overheating. As for the OnePlus 2, we'll just have to wait and see before making any sweeping judgments about potential overheating.