Welcome,
I have iStick several 20w and 30w. I also use Aspire CE5 bvc clearo along with almost all of the Aspire line. I continue to use the CE5 only because it brings out the flavor in one of my juices that nothing else will. There are no flooding problems but the inhale must be slow, steady and rather short or it will result in dry hits. I do not recommend them as there are much better clearos available now.
I recommend the Nautilus mini as it does not have the flooding, wicking and leaking problems that have been reported with the full size Nautilus. OTOH, you are doing so well with the pesky CE5 that you may be able to avoid problems with the full size Nautilus. The Eleaf GS Air and Air - M are not as expensive as the Nautilus Mini and have very positive reports. Below is a link to the ECF GS Air thread. Discussion of the GS Air-M is near the end of the thread. Don't hesitate to join the discussion.
http://www.e-cigarette-forum.com/forum/clearomizers/642824-eleaf-gs-air-fan.html
BTW, the Aspire CE5s sell for $5.- $7 in the US.
Best wishes on your vaping journey.
~ Elaine