I can confirm the above.
I just got my bottle tested for the first time at a dive centre and was told that since it has a non-scuba valve fitted and therefore cannot be used for diving the next test is another hydrostatic in 5 years. They said that the 2 year visual inspection is mainly to confirm that no corrosion has occurred from the dive bottles being submerged in sea water.
So if your bottle has a scuba valve it will be subject to the 2 year visual inspection as well. A "Surface use only" sticker on your bottle will not fix the 2 year testing issue if it has a scuba valve and can
