Is it ok to work in Laravel and CodeIgniter side way? Will it kill my learningcurve ?

Laravel has a lot of things build in that codeigniter does not, but if you use Composer, this won't matter. I have my production system built in codeigniter using several Laravel components through composer (Eloquent, Events...).

It does scare me how quickly and drastically Laravel can change. I built a system in 4.1 about a year and a half ago. My client asked me to create another site using laravel. When I got 5.0, all the file structure had changed, many functions and procedures... It was rather annoying having to learn the new way to do things. All that being said, once I got comfortable with 5.0 (and now 5.1) it makes sense how and why they did it and it works.

If you are a newbie to frameworks, you'll grasp codeigniter much quicker than laravel so that may be the way to go. If you're up for the challenge, Laravel is more complicated but you may get more out of it in the end than learning codeigniter.

This may all change with ci 4.0 though..

Codeigniter is simply one of the tools you need to learn to be a successful developer. Always add more tools to your coding arsenal!