I am biased, I like and regularly fit Evohome Systems.
Addressing your points:
The communication protocol used is very dated (and I am told) not of a configuration that can easily be upgraded.
The system is robust and when setup properly is reliable and maintenance free - apart from yearly battery changes.
It is expensive, the parts pricing alone for most systems -10 zones average - we instal are circa £900. Add to that the installation cost of £390 ( 6 hours) so it is not cheap.
In my view, it is unlikely that Honeywell will undertake a major upgrade. I think that they will introduce a new product, but it won’t be backwards compatible with the current Evohome ( they will probably use a new comms protocol).
It is a “life style” product, it is very effective in larger properties where some rooms are not used on a daily basis and (after the learning cycle is complete) provides a comfortable temperature environment. However, the payback period is probably 8 years plus - hence my use of the term lifestyle.
The earlier poster cited separation distances (300mm) this is only for the BDR 91 receivers and they also need to be over 300mm away from a large metallic object - like a DHW tank! So not really installer friendly!!
Adressing your specific points, if all rads are zoned, you don’t need the control valves. However, if you are not controlling through Open Therm, I would leave them in place and control through a BDR 91. Why? Because if Evohome looses control - or batteries are exhausted, it defaults to operating at 20 degrees C.
Manual control of the radiator valves can be an issue. If heating it set to off and a valve is manually opened it will trigger a call for heat until it ( the temp on the rad valve ) is satisfied or the next set point is reached. If heating is set to off, the next set point is never reached! The answer is to always leave the heating on Normal or Economy mode ( so a set point is reached) i Evohome terms off does not mean off!!
The smart phone interface et al - I have never had a problem or customer complain about loss of service - and I have some very picky Customers! When upgrades are scheduled, Honeywell advise you 10 days in advance and the outage periods are generally 6 hours or less overnight.
Pre installation, you can set up, configure and fully test a complete installation before you fit it in the property. We do this with every installation.
With the customers approval you can remotely monitor and control every Evohome system you have installed.
Honeywell written installation instructions are at best poor / confusing. Telephone support is quick and generally to a high standard.
So, in conclusion, if you want to supply and fit Evohome as part of your business - fit one at home and play with it ( that is what I did and learnt a lot). Don’t try to fit Evohome to a customer as a one off - you need to be familiar with the idiosyncrasies of the system - double binding of units is a common problem.
The above comments are based my experience with Gas and Oil fuelled systems. I would not recommend Evohome for the control of air or ground source heat pumps. It will support those systems, but Evohome requires a lot of on site customisation to be effective for heat pumps.
There is a lot of very capable on line technical expertise for Evohome on Automated Home - particularly with respect to the protocols used in the system (and their limitations). Or on a more simplistic level, Richard at the Evohome Shop.
To conclude, my experience is very positive, but you have to persevere and don’t expect the pay back to cover the cost of savings in energy use for less than 8 years. On the plus side when you move, you take the system with you!!
DHW control. On the face if it I agree with your comments. However, I took the plunge and it will control DHW to plus or minus 1 degree C. A pity that it does not have a legionella cleaning setting ( if that is the correct term) - but I would instal the Evohome DHW option if cost is not a limiting issue.
Hope the above helps
