Out detailed evaluation of spark shows promising, besides being a toolkit it provides a framework for inter coachview communication control addressing, formulas and neatly interfaces with coach view functions using @functionname, except for a few hiccups here and there which have workarounds, i like the service data table and service call for ajax integrations as well as the notification control for application status messages, biggest problem of brazos is that it was feature rich and started initially as a very good toolkit but over time due to catering to too many diverse requirements ended up with a poorly performing toolkit because of very heavy libraries to load.
The flexibility of spark in terms of responsive conditions is also very good till a certain screen size it adjusts automatically and if you need to use a even smaller screen you can put a responsive sensor and change the layout panels and sections e.g. from horizontal to vertical etc.