Is it worth switching from journal 2 to journal 3

We have Journal 2 with opencart 2.3.0.2 ; is it worth it switching to journal3 on opencart 2?

I tend to go with "Don't fix what aint broke"

If it is working for you and does everything you need, then I see no reason to.

I had migrated from v2 to v3 almost 6 months backs because I had nothing better to do then.

1. The admin module is entirely different, and there is a steep learning curve. How you did things in v2 is not at all how things are done in v3. So you can expect a downtime of a couple of days even if you are very well conversant with the theme in v3, since the new admin will slow you down each time you need to configure a new module.
2. As a store owner, there is absolutely nothing v3 offers which is not there in v2. The new things which actually may matter are: Product images on left/right of main image, customization of "add to cart", "buy now" buttons. Additional locations for modules. A few new labels, new Icons.
3. The option to define image sub-domain is in the theme itself. Kind of useless if you already have it configured or have http2 enabled.

Unless you really want any of these features or if have nothing better to do for days, like me, you could switch at the cost of a downtime for a few days.