The main difference between Ra 2 and Homeworks QS would be scalability and programming flexibility.
Ra 2 is system designed around being able to retrofit into a home with regular wiring, so all of the devices are designed to fit into wall boxes, and work in various switching configurations. The devices communicate wireless with each other and rf repeaters. Of course one can install the Ra 2 dimmers in a remote location, and opt for keypad control, but the system design is never truly 'centralized'.
From a programming standpoint with Ra 2 you have:
Scences - a button press bringing system devices to a preset state
Toggles - a button press toggling a load or loads between 2 states (On & Off usually)
1 time clock with the ability to create modes, and events which can be tied to different modes (for example, random lighting turning on and off would be applied to the 'Away' time clock mode, and not the 'Normal'.
A programmed Ra 2 system feels pretty vanilla, but it excels at being vanilla. As soon as you start trying to make it more than it is things get a little crazy.
Where Homeworks really shines is it's ability to be totally centralized from a design point of view. Dimming panels and processor enclosures can be installed in mechanical areas where all system wiring would be routed too. If you need to add an interface, or power supply all the wiring is in one location. Homeworks QS can also scale up to thousands of devices or zones, where Radio Ra 2 caps at 200 (with a few gotchas thrown in there for good fun).
Programming with QS gives you a lot of flexibility with conditional logic (however a little limited at this time) and the ability to dial in the way keypad button presses work and how the end user will use the system.
As far as your specific requests, there is not anything that Ra 2 will not be able to achieve. For HVAC I would recommend the Lutron Honeywell stat (with a remote sensor if you want it out of sight). Having the stat integrated instead of stand alone will be much more functional for you, and many stats can be used for multiple zones, which displays very nice on the app.
I find sensors with Ra 2 kind of suck, because without conditional logic programming they never really seem to do what you want them to do. For example with Homeworks you can have the sensor respond differently based on time of day, or any other factor you find important whereas with Ra 2 that light comes on to the preset value every time.
As far as remote access, Lutron recommends VPN for the apps, so you're going to want to have your installer review the app notes on that topic. Port forwarding does work, however it is not supported by Lutron.
Keep in mind with either system that dimming LED's can be challenging. It is getting easier because the quality of dimming drivers is always increasing, however they can still be quirky. I would recommend testing all your fixtures/lamps before hand if possible. There is a Lutron tool for selecting LED fixtures/lamps on their website but it's getting quite dated as they do not seem to update it much (ever).
As far as price goes, Homeworks does cost quite a lot more, maybe 50-60% more than Ra 2. One can expect to pay about $300-400 per zone for an installed Ra 2 system (depending on a ton of factors), and Homeworks about $550-650 per zone. Of course prices will vary from place to place and how the system is designed.