Crucial M4 128gb - worth upgrade?

It's been 4 years since my last major upgrade, gone through a couple of GPU's in that time but that's the height of it.

Thinking of moving onwards and upwards in the next couple of months - mobo, cpu and RAM.
Anyone have any opinions on whether it's worth upgrading the SSD? It is working flawlessly and capacity isn't an issue as it's for windows and applications only - I have a 1tb Hybrid for games etc.

Would I notice any improvement in buying a new SSD as the boot drive or have SSD's got to the point of the Law of Diminishing returns now? It is SATA III and 6gb/s which is what most of the current budget SSD's seem to be anyway. As I say it's been 4 years since I've even looked into them so I'm a bit out of the loop.

**EDIT**

Just seeing that the mobo I plan to get supports 32gb/s M.2, maybe this would be the ideal upgrade path?

You wouldn't notice a difference unless there was a problem with it. I would ensure it has the latest firmware and run a benchmark (post it here) to check its running as expected

My M4 128gb started to die about 6mths ago. It is about 3yrs old maybe.

I've chucked it in something as a cache drive.

Deffo worth replacing it now, it's only a matter of time.

Actually yes. I had a M4 in this PC until a few weeks. Needed more capacity so upgraded to a Samsung 850 Evo and I have to say the PC is definitely a little bit more punchy.

Moved from a 64GB M4 to a 250GB 840 EVO. Not really noticed any performance difference. I only really upgraded since price per GB was getting decent.

FYI I thought my M4 had failed so I ordered a new bigger one. But after a chat with crucial tech support it turns out I needed to force it into Active Garbage Collection.

http://forum.crucial.com/t5/Crucial-SSDs/TRIM-and-SSD-performance-why-is-it-important/ta-p/100276

Disconnect the SATA cable, boot the PC, and leave it over night. SSD is idle and AGC does its thing. That SSD is now in my laptop and it's 4 years old - it's faultless.