My have strong opinions about plain guage spokes. They are cheaper and that is the only reason to use but given the low cost of Sapim Race what is the posint. If you need the stiffness of a 2.0mm spoke you will also need the fatigue resiatnce (to to the load the wheels must be carrying) of a 2.3mm elbow e.g a Sapim strong spoke.
So use DB 2.0mm/1.8mm/2.0mm spokes they are cheap and robust and will give good stiffness on the XM317/XT M737 parrallax hub combo. You can use the thinner sapim Laser (2.0/1.5/2.0 on the front with no issue and depending on your weight Sapim Lasers on NDS rear or maybe NDS/DS rear. It will also depend on the kind of rinding you are doing.
My wife MTB wheels are M563/M565 hubs on XM317 rims 32H and Spaim Laser spoke front/NDS rear Race DS rear. This bike is used mostly for winter commuting in the snow and ice and it works she is 85-90kg (she does not rear this site). In am 82kg and and use Laser spoke all the time for my road and MTB wheels see the wheels I built above. The one in this thread are very stiff.
The Shimano series rim brake hubs give excellent bracing angles so thinner gauage spokes work quite well.
For most road wheels I use Laser spokes front and NDS rear and Race DS rear unless the rider is quite heavy then Race spokes all round. If there is an extra load on the rear wheel then Strong spokes come out for the DS rear. If the wheels are for a heavily loaded touring bike the Strong single butted 2.0/2.3mm will get used all over the rear wheel.
For MTB wheel DB 2.0/1.8/2.0 is what I normally use unless they are race day wheels, wheels for ligther riders, wheels intended mostly for road use in which case Laser spokes can be used sucessfully.
I find plain guage spokes completely unnessecary for most people. They make wheels cheaper and heavier than it need be that's it.
