I've never seen an SLG3000, but have you tried the new HLSL effects in mame? Scanlines + a lot more. I actually bought a new video card just so I could use this. Haven't had much chance to play with it yet, but it looks like you can get pretty much any crt like look you want if you take the time to tweak it. Awesome!
What exactly are your PC specs and video card, does the new effect slow down the performance,
Sounds like you got the SLG3000 working better which is good, but since you asked, here are my specs:
AMD Athlon II X2 215, 2.71 Ghz
2.87 GB of ram (actually 4 GB, but I downgraded from 64bit Windows to 32bit which I think is what reduces the ram)
nVidia GeForce GT 210 PCI-Express Video Card
The new effects slow down performance big time. With this setup, I get about 75%-80% frame rate on the games I've tried, which I fix by setting frameskip to 4 or 5, then it's fine. I'm planning to upgrade to 64bit Windows and 64bit Mame which I figure will give me enough of a speed boost to get full speed or at least close enough that I can attain it with just a little frame skipping.
If your system can handle it, I'd still give it a try as you're obviously interested in CRT like effects and this does a great job.