Are there any significant differences between a cast iron base or a steel base for a 4" x 36" belt sander? I know that cast iron tends to be stronger but crack more instead of flexing like how steel does. I also know from some forging videos that cast iron doesn't conduct vibrations as well, which is why cast anvils tend to be worse for forging than a forged anvil. Are there any other differences? Does the better vibration control account for much when operating a belt sander for say, a small wood shop?
I can't imagine you would be applying enough pressure on a belt sander to worry about cracking.
It is definitely true that a heavier sander will not vibrate at the high frequencies generated by normal sanding.
Steel is strong and light, so it might be better for a portable belt sander. But cast iron might be better for you in a workshop.
In the end, with light sanding, you might want to do some shopping and look at the features then find the best price to performance ratio to make your decision.