The mobile joomla component works pretty well with the available positions for each platform currently.
However I'm all for reducing the amount of work and simplifying the site backend when developing a site and try to utilise the same position for multiple platforms, favouring the mj_all position, styling each via the custom.css.
This works great currently and saves duplicating modules targetted at different positions, without using positions for other platforms, some of which aren't referenced correctly, or at all, in certain templates.
Would it be posible to incorporate more than one mj_all position for top/middle/bottom, two would be an improvement, three would be ideal, to allow alot more flexibility in the site configuration?