You will love Autopsy, by Yanone
http://www.yanone.de/typedesign/autopsy/

Comparing all the outlines is going overboard. When you check everything in Prepolator just make sure that the example interpolation works. Then eyeball comparisons on paper by formatting the fonts with a nested paragraph style that loops through character styles and repeats at the beginning of a word. If the masters are drawn correctly there shouldn’t be anything strange going on that you won’t see on paper, and it’s easier to see what’s going on with solid shapes than with a pile of outlines.

I second Autopsy.

"formatting the fonts with a nested paragraph style that loops through character styles and repeats at the beginning of a word"
! That's possible? Oh man.
How do you tell ID to «loop through» character styles?

Both Autopsy and Prepolator sound quite right for what I had in mind thanks for the pointers.

How do you tell ID to «loop through» character styles?

Here is how to do it with four fonts:

• Set up your repeating characters as if they are words separated by spaced, eg. “AAAA BBBB CCCC”
• Create four character styles, one for each of the fonts
• Create a paragraph style and nest in each of the four character styles. One, two, and three operate “through 1 characters”, four “through 1 words”, and then add a final style to “repeat through last 4 styles”.

I wonder if Autopsy and Prepolator would also work with Arabic fonts (complex scripts right to left)...problems are likely to occur if more than just individual unconnected glyphs are to be displayed.

Hi Vladimir, how are you my friend! I wished to write you for a long time! :)

I have understood more or less a 5% of Dunwich Type's suggestions… But maybe it's just my difficulty to use automated methods… :)
Besides the potential problems suggested by Vladimir, I would add that his type family (if it’s the one I think) was not drawn through interpolation, but independently weight by weight.

P.S. If it's an uppercase Thorn, it shouldn't have a descender.

Superpolator is mac only? right?
Is there something like that for PC (Other than the great remix tools by Tim Ahrens)?

But maybe it's just my difficulty to use automated methods… :)
... I would add that his type family (if it’s the one I think) was not drawn through interpolation, but independently weight by weight.

Hello Claudio! Indeed I am extrapolating to six weights the Latin glyphs of the two weights of the Arabic AlQuds family. Your generous and careful craftsman-like revision of my two Latin fonts (added to the revisions by another kind volunteer) is anything but automated. And yes no MM interpolation was used. I will revise the capital Thorns thanks.

I now understand that Autopsy (which wins the prize for the most gruesome logo for an excellent software, after the original roadkill logo of Irfanview ! :)) and Prepolator are OK for Arabic since they only compare individual glyphs not text strings. Everything considered I think I will just use the method I outlined above (graphic pun intended) and a similar method using layers in Illustrator to compare the glyphs. Thanks to all.