MrSurfacer 500 vs. MrSurfacer 1000- Any Practical Difference ?

Yeah, there is a difference.  

I use 500 to fill gaps that putty would be too thick for.  For example, 500 is good to fill gaps that are as big as scribed panel lines on a kit.  And you might need to apply 2 thick coats to fill those.  1000 is thick enough to fill hairline gaps, scuffed up surfaces or butt joints.  1200 is good for priming.

500 is great for creating the rough surfaces that you want.  I've used 500 to create the ablative coating that you see on bombs stored on aircraft carriers.  1000 might do the trick but I think it will be too thin especially at 1/25 scale.

Another choice that may be good for you would be Mr. Dissolved Putty.  It would be like having Mr. Surfacer 100 or something.

Thanks for the info, Fly-n-hi .

I kinda presumed the difference might be more in terms of the amount of ( putty? ) dissolved in solution rather than the strength of the carrier liquid base.

I'll pick up a bottle and try it on a piece of scrap styrene.

As for Mr. Dissolved Putty, I've never before heard of that, but I've only just recently returned to the hobby.

Thanks again for the information.