I can't really comment on the hive all, never used it or installed. It's a simple all on the smart phone and a remote thermostat but I don't know if it's WiFi or 4G connection. Never met a customer with it yet!
As for Combi boilers, Worcester gas boilers are pretty indestructible but, condensing boilers have a10 yr lifespan! That's just how it is!
DHW cylinders? Yes I would promote them above a Combi boiler. Combi boilers have more to go wrong and invariably will!
DHW cylinder connected to solar thermal panels (not PV) can give you up to 80% of your DHW. You can also connect a bivailant system to this, meaning two forms of heat, a log burner with a back boiler for example or an oil back up boiler or ASHP.
A bit of planning involved, type of heating, how many indirect connections to DHW cylinder, solar thermal viable? Bivalent?
Or just rip out the old Baxi Bermuda and stick in a Combi wall mounted! Space? Yes! Cost? Less!
Your choice sir, I'll not start on biomass, just not worth the effort!