The maximum sample rates of the Saleae Logic devices will scale down as more analog and digital channels are enabled. In order to save memory on data captures, you can choose a slower sampling rate than the maximum.
For example, Logic 8's digital channels have a maximum sample rate of 100 MSPS on up to 3 channels, 50 MSPS on up to 6 channels, and 40 MSPS on up to 7 channels. Enabling the analog channels will also change the available sample rates of the device.
To browse all possible sample rate combinations of the Saleae Logic products, download the Logic Software and check the sample rate options for your specific device. You don't need to have the device connected. This option is also perfect for evaluating the software and its features before purchasing the Saleae Logic products.