In the end I ended up getting the flex-arm set (
as this was cheap),
In the end, my first UW setup is following:
Olympus XZ-1 $400
2 spare akkus, charger $10
Olympus PT-050 $211
Olympus PTWC-01 $369
Strobe set $630
(INON S-2000, Fibre sync cord, Flex-arm 36cm, Double slot tray)
Fantasea 44 LED light $60
Flex arm 18cm $20
Coiled lanyard $30
Close-up lens +8d $5
+ other minor bits
All in all, I think money well spent and a good base to build upon.
One thing bothering me was how front-heavy the system was because of the PTWC-01 converter, so I bought a floating wrist strap (similar to this:
Amazon.com: Pentax Optio Floating Wrist Strap - GWP: Camera & Photo ) to mount around the lens barrel and balance it out. Hopefully that’ll fix it.