Should I continue to work with CodeIgniter in an existing project?

For the third year now we have been offering the ImageCMS project originally created on the basis of Codeigniter. During this time, much has changed in the framework market, especially the apparent decline in support for the Codeigniter framework and the large increase in the popularity of the Yii framework. Disputes about the benefits of different frameworks do not subside. Let's try to relate the question of choosing a frame with ImageCMS and find out why we are working with CI.
Several reasons that we consider essential to continue working with Codeigniter:

1. Codeigniter is easy to learn, there is excellent documentation, specialists who have worked with php very quickly get up to speed and start working with the system;
2. The community of our product already has more than 1,450 people, the system has also been installed more than 20,000 times. After changing the framework, users will not be updated and will have to support two products at once, the old version for about a year;
3. High-speed performance and protection against hacking are in principle equally well thought out with a slight advantage in the direction of Yii. Our choice has the main types of protection and, if necessary, allows for the completion of additional ones;
4. It is worth assessing the future of frameworks. Let's make a small comparison:
   Today, Google evaluates the trends of popular frameworks as follows.

Trend CodeIgniter

Trend Yii

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Zend Trend

Thus, we see that although Codeigniter is inferior to Yii, especially in runet, yet its popularity continues to grow, this framework is not going to give up in the future.
What are the possibilities of developers and communities. Take simple community statistics in the forums:

Name	Yii	Zend	Codeigniter
Number of participants in the official forum	44188	16259	163700
Number of Russian-language forum participants	2313	2373	2394

Number of participants in the official forum

Number of Russian-language forum participants

Now consider the strengths of the YII and the advantages of the transition:

• Caching with the ability to change backends (File, Memcache, etc ...);
• Separation of access rights;
• Models;

To summarize, a team of ten people could have finished Codeigniter in this plan for a month, with this community resource, the framework is more than promising.
All these advantages can actually reduce development time, but let's imagine what the migration to a new framework will give us.
In connection with what is the question, is it worth working on a complete update of the framework for our project? I would like to hear the opinion of the community on this topic.