Of course I would recommend buying :-)
…But, yeah if you are only using one feature like Sass preprocessing (for example) then yes there are lots of free alternatives including the command line.
Mixture’s live reload / style injection requires no plugins or tags and works across pretty much all devices and browsers. We make it easy to multi-device test and we also list all connected devices and let you debug these devices easily with weinre.
With regards the Major and Minor updates… this is very standard practice for one-time fee software. If a brand new “major” version is released in a few years we may charge an upgrade fee (majority of software you buy does this – even sublime – to continue supporting users and releasing updates / improvements costs money after all), we wanted to be clear about this which is why we added that wording.
Email me and we can talk about your trial period: neil dot kinnish at mixture.io