If your data is changing fairly often, even only on one channel, then there is no savings at all. Note that transitional timing is usually not available at high sampling rates, right when it would be most useful. Only if your circuit has long periods of inactivity between events. However, a long memory buffer will also provide the same benefits, while working up to the full speed of the analyzer. With longer memory, you can both maintain high sampling rates, giving you better waveforms, and see longer duration events in their entirety.
Memory is used to store the input waveform.
Consequently, the longer the memory, the longer period of time that can be acquired. Or, more samples can be taken within the same period of time at a faster rate. Often, the known error occurs some time after the actual cause. Longer memory allows you to trigger on the known error, but also capture the sequence of events back to the root of the problem. It is a long buffer that allows you to see both the problem and its cause.