Sharpie S-Gel is permanent on porous materials and does not bleed. It doesn’t smudge and provides a wonderful writing experience. It is possible to clean Sharpie gel using acetone, esters, and ketones, but this will damage the material.
Yes, E6000 is toxic. It is an industrial-strength adhesive that is used mainly in manufacturing as well as DIY projects at home. It releases toxic fumes, and so you should wear a mask or respirator when using it.
The reason why Jon and Bob’s products have been in the limelight is not because of a lack of competition. If we compare their products with compost tea, for example, the benefit of using Jon and Bob’s is that it has made gardening simple and affordable for everybody including everyday gardeners.