Do you need to purchase more than the basic 5 Gigs of free iCloud storage if you have more than 5 Gigs of all data that can be stored on iCloud if you subscribe to iTunes Match?

I purchased an additional 10 Gigs of iCloud storage in 2012 for my iPhone 4S and iPad (3rd Gen Wi-Fi) for $20 per year through my iPhone carrier AT&T using IOS 4.3 which has been kept updated to IOS 6.13. In 2012 I purchased an iPad 3rd Generation with Wi-Fi only and at the end of my one year 10 gig upgrade I noticed that I had not used any of the additional 10 gigs and was not going to renew the additional storage. However, I decided to move all of my MP3 music library and copy my remaining CD collection of music (a couple hundred CD's) to my Windows Computer Hard Drive so that I could keep them safe.

As I started purchasing new Albums from iTunes I decided to allow iTunes to store all my music in case my Hard Drive crashed. I did not purchase iTunes Match but all of my collections appear to be stored on iTunes as the storage cloud appears on my Apple devices which use the same Apple ID. A week ago I purchased another iPad (4th Generation Wi-Fi only) so my wife and I could use them at the same time. I kept everything under the same Apple ID because I use a lot of music creation apps like AmpliTube, Drum machines, Guitar Pro etc for creating music as well as Photo Apps for my Photography hobby and I wanted access to the apps regardless of which device was handy (including connecting the 2 iPads together for music looping and more).

I still don't see any of the additional Ten gigs used as less than 500 Meg's are backed up into memory from each of the three devices.

QUESTION: What is the advantage of an iTunes Match subscription if my library of some 10K songs are already stored on iTunes and I have not yet exceeded the initial 5 gigs of free iCloud storage? I keep my library in MP3 format for convenience and convert my music library to between 192 and 320 Kbps. Given the choice should I cancel the additional iCloud storage and subscribe to iTunes Match. Is iTunes Match a replacement for purchasing additional iCloud Storage?

Confused as to which service I need?