I ride a hybrid that is proportioned a lot like a road bike (straight horizontal top tube, handlebars several inches below the properly adjusted seat height, 28mm stock tires).

The whole time I've had it (15 months), I have felt like I was leaning too far over to hold the flat handlebars. I have raised the stem to the top of all the spacers. I have gotten a shorter stem (cheap one, to experiment). I have moved the seat all over the place forward and back. I have the seat about as far back as it will go now, and that seams to be the best it has been. It helps balance my butt in relation to my feet, but Doesn't seem to quite be enough.

Has anyone here actually bough and used a stem riser and been happy with the results?

BBB BHP 21 works well , but you have to Import them your self Now wiggle.com | BBB BHP-20/21 Stem Extender | Oversize Stems

US distributor went away.

I played around adjusting seat position and handlebar height on my Giant Escape last summer and found the sweet spot for handlebar height to be at least 2" above seat height. I also changed out the seat post to give me more setback. There is a difference between stretching down for the bars and stretching out for them. You can find your own sweet spot by noticing the pressure you feel on your arms versus your seat. Take your time finding that happy balance between your butt and arms.