DIR is stated as a system that can be used in virtually any diving environment.
With this is mind a regulator that fits this description would also be appropriate. While not necessarily something to worry about in Asia, colder environments have unique requirements. I have heard of Scubapro's free flowing from people that know better than me in temps below 6 deg celcius. I am specificially referencing the MK20/25's of this world, not the diaphram designs.
Apeks on the other hand can truly be used everywhere, from temps below freezing to tropical waters.
Having said that, JJ uses Scubapro as does Casey Mk. George, Reinhard and Michael on the other hand like Apeks. What this say's is that either design/brand is more than appropriate for the majority of people considering the lead explorers in the DIR frame work use both brands. If your plans ever take you to colder waters i would personally recommend the Apeks, if you will only be diving in warmer environments, get whichever is cheaper and gives a better hose routing.
I personally have used Scubapro's for the last 6 years, they have been great barring two 1st stage failures at random times, including after a service.
It is for this reason, along with the "all environments" concept that induced me to recently purchase 5 Apeks regulators. I will continue to use my Scubapro's for singles but the Apeks will be destined for my technical diving.
I personally also like the fact that Apeks can be assembled/disassembled with an Allen key while the Scubapro's require some specialist tools. Both brands use standard parts kits, so no issues there.
Recommendations: Apeks: TX 100/DS4 for twins, TX50 DS4 for Deco
Scubapro: MK25/G250/S600 all round.
Good Luck and safe diving,
Gareth