5400rpm drives have higher latency and will be slower.
My suggestion, since you have two spots for drives would be to use a SSD on one, for the os, and parhaps a few games.
Use the other for storage. With a ssd, I would be OK with a 5400rpm drive, but 7200rpm would be faster.
For data security, you need EXTERNAL backup.
The value of raid-1 and it's variants like raid-5 is that you can recover from a drive failure quickly. It is for servers that can not tolerate any interruption.
Modern hard drives have a advertised mean time to failure on the order of 500,000+ hours. That is something like 50 years. SSD's are similar.
With raid-1 you are protecting yourself from specifically a hard drive failure. Not from other failures such as viruses, operator error,
malware, fire, theft, etc.
For that, you need external backup. If you have external backup, and can tolerate some recovery time, you do not need raid-1
Understood. I will have external backup as well. Just trying to get a sense of what people think on the difference in speed because I wouldn't mind having RAID 1 as well if the loss in performance is not noticeable.
Raid-0 will give you nice results in sequential benchmarks, but not in everyday usage which is mostly random, not sequential.
Raid-1 will cost you a bit, due to the need to do double updates. But mostly, it will hurt you because the access times of 5400rpm drives is longer than with 7200rpm drives. That shows up in random access times, which we do mostly.
If you have any option at all, buy a SSD. It will transform the performance of any laptop.