The problem with JOBO tanks popping the lid off can be cured by using a red hot needle to piece the top cap. This allows the release of the gas pressure caused by mixing the developer and blix. If you use the inversion technique it is a simple matter of putting a small strip of adhesive tape over the hole, or even simpler, use your index finger. With the cap intact, I have never had a jobo tank leak. I also have a quite old 120/35mm Jobo tank with a screw top and the red top is of a different design but this has the hole already made.

I also have tanks made by Durst (Centre loading plastic) and unnamed stainless and non of these leak , - I must be unique, but when they are in use, they stand in a bath of warm water. So if there was a leak it may go un-noticed, but mine don't anyway.