You should work with your reseller on the Sage 100c change.

If your extended solutions work on your current Sage 100 version, they'll work with the same Sage 100c version.

The impact for users is Sage 100c has several features that are not available in the non-100c version.

Eric,

What version of Sage 100 are you using presently? 

Do you use payroll? 

Sage implemented a license key update program starting with Sage 100c v 2016 PU 2.

Versions of Sage 100 and Sage 100c which auto-update keys:

2015.5+
2016.2+
2017.0+

Note: Versions 5.20.3 (2015.3), 5.20.4 (2015.4), 5.30.1 (2016.1) will have the ability to update the payroll expiration date with the Update button by installing the Hot Fixes based on version KB 83158 ( https://goo.gl/NnlQbY ).

Note: Some third parties such as Job Ops may require a new registration key if the Sage USER KEY (not customer number) changes. The update process does not change customer or serial number but the Sage 100 USER KEY changes.

To force an auto-update of keys:

- Open Library Master, Setup, System Configuration, Registration
- Click Update button

If keys do not auto-update you can try to force an update of the product registration:

- Open Library Master, Setup, System Configuration
- Click the Registration tab
- Click Activate or click Edit then click Activate

Depending upon your version of Sage 100, you may be able to automatically update the keys within the product as noted above. This might not require you to install the latest Sage release, however, I typically would advise staying current as the window of support for different versions can be as short as 18 months ( product update eligibility ).

Your end users will have the ability to switch the menu style ( classic - old style , standard - new Sage 100cloud style).

So far as I'm aware your Extended Solutions are fine and you only need to update them if you also upgrade Sage 100.

There are other various 100cloud benefits of which your reseller or Sage is best to advise you on. 

Eric,

Your Sage Partner/Reseller would be the best contact.  Sage Sales has marketing information on the differences between Sage 100cloud (formerly Sage 100c) and Sage 100 but the partner can help you evaluate subscription changes and upgrade possibilities depending on your Sage 100 version (upgrading to the latest Sage 100 with 100cloud/100c subscription may allow you to add some connected components that could be useful to you).  

The Sage Knowledgebase has some information on the changes in Sage 100cloud/100c such as Knowledgebase article 82363 "What is the difference between Sage 100 and Sage 100cloud (formerly Sage 100c)?" available at https://support.na.sage.com/.  Or article 38011 "How to add additional user licenses or activate Sage 100cloud (100c) ". 

You don't need to install additional software in your same version of Sage 100 (if compatible), to "unlock" Sage 100cloud/100c features in the product you would just update your Sage 100 registration screen with the new 100c product keys. See Wayne's note here regarding the Update button in certain Sage 100 versions to auto-update keys.

Additional note of just a few new features in Sage 100cloud/100c: (based on new Standard Desktop)

•Sort module, menu, and menu item lists
•Menu displays only tasks the user is authorized to access
•Custom Theme settings (fonts, colors, backgrounds, button options

All of the prior comments are valid and it is always good to be cautious.

Generally the switch from 100 to 100c is just a matter of updating the unlocking keys as 100c and 100 are actually installed from the same install files.

Now if you are upgrading between versions 2016, 2017, 2018, 2019, etc. that is another story entirely.