Hi, you're welcome, thanks for trying my plugin.
Yes, all the slideshows are the same size by default, but you can use metadata to change the size. Check out my tutorial on multiple slideshows with different sizes for more info.
Meteor Slides uses the jQuery Cycle plugin to power the slideshows, this script is expecting to get a specific height and width. Some of the sizing is handled in the stylesheet, but the JavaScript needs to know and use the size to get to all work correctly. But because Meteor Slides is responsive, the height and width in the settings are only the max dimensions, it can shrink from there to fit other sizes.
Have you run into any issues with the sizing or is there something you weren't able to do?