Your choice may be fine for you, but is also beside the point. I wasn't looking for your choice of what to do, but how to do something else.
I may have no choice but to convert all my images to png or another format (to use Scribus) which would take me days if not weeks, or buy InDesign.
If can avoid the expense of InDesign I would like to, although I'd prefer using software that works for me, rather than software that I would be "working for".
Also, photoshop pdf's contain layers editable with photoshop, whereas converting to other formats like png or others merges layers and increases the time needed to edit images as they would need to be recreated from the photoshop files anyway.
Scribus would have a lot more users if it can be shown to equal the power and usability of InDesign. "probably" not is not an answer but an opinion. I was hoping for discussion with someone who has extensive experience with Scribus and pdf images.
In your Adobe Reader under Edit Preferences check "Show transparency grid", and open this pdf:
http://coastcoffeenews.com/files/images/imagewithtransparentbackground.pdf, then try putting that image in a Scribus image frame. If you can find a way to retain the transparency in a Scribus image frame please let me know how you do it.