I've had a lot of tweaking an generally a few problems when using a Scandoubler but i've found out a few things;
------------------------------------------------------------
A600 (A-RGB) + Indivision SD/FF + 17" LCD (VGA) =
PAL - Too low frequency for the LCD wich results in a constant errormessage onscreen, but with a ok picture behind it. Picture offscreen on top and left sides. Tweaking with the pot-meter on the Indivision a lot to get a stable picture needed. For a LCD to work properly with a Scandoubler, you need the rare models that can sync down to 50Hz. Search the net for these.
NTSC - Almost too low frequnecy but good enough to work. No errormessage. Picture is crisp, clear, strong colours. Picture still offscreen. Tweaking with the pot-meter on the Indivision a lot to get a stable picture needed. Picture looks pixelated because of LCD technology. NTSC is not a good signalstandard when using the amiga for PAL-games and software, so this is not a good overall solution. The games and wb I tried worked good though.
CD32 (A-RGB) + Indivision SD/FF + 17" LCD (VGA) =
Same as above with both PAL and NTSC. Using SX32, that's why I could test with A-RGB on the CD32.
A600 (A-RGB) + Indivision SD/FF + DLP Projector (VGA2DVI) =
PAL and NTSC - After tweaking the pot-meter, very good picture, as I remember also no offscreen problems. Not so pixelated either, because of the DLP technology (kind of a CRT/LCD combo). The modern projector is a flexible and highly signal compatible piece of equipment and works good with scandoublers, in my experience.
CD32 (A-RGB) + Indivision SD/FF + DLP Projector (VGA2DVI) =
PAL and NTSC - Same as above.
------------------------------------------------------------
Overall a standard LCD is not the best solution, but you can make it work if using only NTSC. If you get hold of a LCD that can sync down to 50Hz you get a nice picture with PAL compatibility.
Using a LCD-tv is probably better because it is more compatible, but these also have their problems like being widescreen native so that you loose a lot of screensize when using it with 4:3 equipment.
Using modern Projectors produce very good pictures because of their compatibility but blowing your wb out on the big screen isn't always what you want to do, so unless you're a gamer only type..
Using a CRT is probably the best solution picture and compatibility wise but then again you loose deskspace etc.
I must state that these tests where done with the high quality, recently made Indivison SD/FF and I have no experience with older Scandoublers/other equipment.
I have spoken to Jens Schönfeld earlier and he has said that he is working on a new, better SD/FF that eliminates several problems, among them the "too low frequency on LCD's" one.
System Details
Amiga 600 Project:
M-Tec w/8Mb
68030@40Mhz + FPU@33Mhz
1Mb w/clock ram upgrade
IDE2Flash with 2Gb CF-card
New chassis
New original Competition Pro sportsticks x2
Indivision SD/FF
Original OS 3.1
Amiga CD32 Project:
SX32 MK2 w/8Mb
680EC020@20Mhz
IDE2Flash with 2Gb CF-card
New chassis
New original CD32 gamepads x2
Indivision SD/FF
Original OS 3.9