Here's an update on my situation:
One of the steps I took in trying to resolve this nightmare AVR<->PJ issue was to take my Pioneer AVR 1019AH back to Best Buy and while there I found out they had the VSX-23TXH (Elite) for 100 off AND I was able to use my 12% Best Buy Rewards certificate so I got it for about 200 off the current retail price.
Anyway, my problem persists if you can believe it or not.
This Elite AVR is simply sweet, especially with the 2 HDMI outs I can definitely use (regular every day viewing on an LCD HDTV and all the good stuff on the projector (once I get it working)).
So basically, now with this extra HDMI out I was able to try the following:
AVR = Pioneer Elite VSX-23TXH
PJ = Viewsonic Pro8100
HDTV = LG42LB5D (42" LCD)
PS3 connected to HDMI "BD" input on AVR.
HTPC connected to HDMI "1" input on PJ.
HDMI "1" output from AVR connected to HDTV HDMI "1".
HDMI "2" output from AVR connected to PJ HDMI "2".
With AVR set to output from both HDMI outputs at once.
HDTV set to HMDI "1".
PJ set to HDMI "2".
PS3 is source.
Image appears on HDTV, nothing on PJ.
Now I switch PJ over to HDMI "1" (HTPC).
Voila, picture appears.
I tried different cables (all which I know work 100% - tested).
I tried manually forcing the outputs from the AVR instead if just saying "both at once".
I tried different input/output combinations.
So in summary:
Still no damn working AVR<->PJ connection.
Any Source -> AVR -> HDTV *works fine*
Any Source -> AVR -> PJ *no video*
Any Source -> PJ *works fine*
Called Pioneer and Viewsonic Tech support on friday.
Pioneer was closed, their voice system announced "holiday" so it seems they decided to have a 4-day weekend, great.
Viewsonic tech support is 24/7 except designated holidays but they have no idea what could be going on, my case has been 'escalated'.
If by Wednesday next week Viewsonic and Pioneer can't tell me what's going on then I can only conclude I have a funky projector because although it works direct with sources and not with my AVR I'm on AVR#2 and I tested its outputs and I know they work.