From my limited, but sucessful, experiences use rattle can paint I will try to explain what I learnt.

The final finish is all reflected in the preparation you put into the item you are going to paint. Get it as good as you can, remove all the old paint and smooth it over using 600 grit wet & dry. Degreasing the item using sugar soap wipes helped get them clean enough for paint. Acid Etch Primer is a must for bike parts, a couple of thin coats is enough. Between coats bake the paint in a cool oven. 50C is about right for 10 minutes. I used metal garden twine to hang the items from the oven shelf. For the top coat start with a very light dusting. Don't go heavy or you will end up with a mess. Be patient. Bake between coats remembering to have a window open as the fumes can get strong. A couple more light dusting coats and a final bake at 150C for 30 mins. If you are going to lacquer over the finished paint you need to be aware that lacquer is much runnier that the paint so apply in very thin coats.

Tried Montana myself, very nice spray cans but Matt only and I had a nightmare with it in the end. Took it to a profesional in the end as it wasn't worth the hassle, and I was on a limited budget too. Next time I know to get it done right first time!

They do gloss too. Great range of colours. Not very hard-wearing though.