I sort of fall into two camps at the moment as I have one site, my principal site on Classicpress and one, which is sort of semi-mothballed, on WP4.9
I upgraded my main site from a very early stage, as I did not like gutenburg and the direction that WP was going. I thought I would take the risk and move my main site.
Why haven’t I done the same for the other site? Well because at the moment, there is no advantage, and eventually, I can see me going back to WP, not through wanting to but by having no choice.
I have an ordinary news site, that rely on plugins, which I know will eventually stop working with Classicpress, plus at the present I also have a free theme as there is no point in buying one as compatibility with Classicpress cannot be guaranteed.
At the moment, I truly want Classicpress to succeed, I want a lighter CMS and a plugin directory, and I imagine that if we could provide this, then we would be able to target the 4.9 users more successfully, saying that we are lighter, faster, more secure and have a full range of plugins and themes 100 percent compatible.
Unfortunately, until we reach this point, I feel we will always fall under the radar, with the existing 4.9 users slowly upgrading to WP 5+ as they will have no choice as their plugins start to not be compatible, and then we will have missed our chance.