Hey there!
I personally like and use the 190 brush for Studio Tech. I like the control and coverage that this brush allows, plus you can get to all the nooks and crannies..examples: the area around the bottom of the nose, the hair line, and near the inner corners of the eyes. Personally, I'd use the 190 over the 187. However, you can use the 187, just keep in mind the application will be sheer and there is more work involved swirling the brush around. I would also think you'd get some streaking from the brush bristles on the 187, so blending will be needed after the initial application.
Have you used your new Studio Tech yet? I think it's a great product and I love the coverage and blendability that it offers. I hope you'll like it!