For 1/2 to say 3/4 of full velocity loads, I'd give HP-38/WW231 the nod. A bit better load density, not as peaky as I understand, a little easier to see in the case perhaps, and I like the pressure curve of it better - Figure between Bullseye and Unique in actual use, and a very nice propellant for lead bullets in my experience. It is a bit "dirty", even when pressed a bit, leaving behind unburned granules. As mentioned if going really light, TG might serve you better, but HP-38/WW231 has been around a very long time, doing a great job with a wide variety of components loaded to a wide range of velocities.
FWIW, I knew a commercial loader who used WW231 for all of his commercial .44 Mag loads, using 240 grain cast bullets he produced. Loaded them right around 1000 fps as I recall.
I don't have 200 gr cast test data, but I did test some 190 grain LSWC with 9 grains of HP-38/WW231 in my 6.5" Model 29, and got:
1163 1115 1096 1142 using CCI 300 primers
OK by me for such a light bullet, and kinda low load density. Good luck.