@bruno.intuitive, I think this is a very wise decision… but Im not sure you can do alot of hacking/augmenting without firmware support…
however, I think this is only achievable IF you open source the firmware.
actually, I’ll take that back a notch, you could also publish exact details of the hardware and how it relates to the mcu … e.g. mcu spec, firmware upload procedure, what digital pins are used, and how…
or produce an api (frankly, the lower level the better)
but honestly, both are quick a lot of work, and you will be fielding a lot of tech questions, thats reason most manufacture just publish the firmware, its just simply easier… it just lets developers ‘get on with it’
dont get me wrong, as a developer who has sold software, I understand the business decision behind keeping software/firmware proprietary… the value of IP, and for sure, its a bold move ways from the idea that this will protect you from a clone.
but honestly… the deal is simple…
if a product is keenly priced (and I think Exquis is!), the frankly 99% of people will just buy it…
even if you made both the hardware and software completely open (*), sure someone could build/make there own, but the reality, is most dont have the skills/time to bother doing so … esp. at the price you offer.
on the flip side, open sourced products are more attractive to potential customers (= sell more of your product) , since
- future proofing
- devs are more interested
- hope/possibility of ‘community firmware’
- possibility of devs helping you with bugs/issues… feature requests.
don’t get me wrong, you’ll be luck if get a handful of open source devs interested… we all have more than enough ‘projects’ on the go 
, but get one or two keen ones, and you’d be surprised at what they can do for the community … and for you too (if you allow contributions back into main code line).
for sure, as an open source developer, Im an open source advocate… and have seen that, generally, fears companies (cloning) have for releasing open source - don’t really happen… and if anything, the general positivity from open sourcing, really sets you up in a much better position with the community.
but as a I said, I do understand why companies want to retain IP (and have done it myself), and totally respect that it is for each developer, their decision !
one parting thought (though feel free to reach out to me).
I’d say think about it now… I personally would never buy/back a product that was ‘thinking about’ the possibility of open sourcing, Id always want that commitment up front.
anyways, open source is just an interesting option - Im sure you will be very successful without out it.
and I do wish you every success regardless, with both kickstarter and the product more generally.
take care
Mark aka TheTechnobear
(*) this is particularly true because you value add with your app