Just out of curiosity if you wanted to go all out and create a Frankenstein's NAS based on XPEnology, is there any physical limitations as to how many disks you could add to a system? Judging by the real steel hardware there are some limits as to how many expansion chassis can be linked and that physically limits your theoretical number of drives, but is this limitation also hard-coded in the software? 
Say you used one, or even multiple raid cards with expanders, maybe also mixed those with all the motherboard ports, you could quickly go far beyond the emulated 3615/17's maximum drives even with expansion chassis. Would the software still be able to handle this or would it put a definite stop at some set point?
I assume that maximum volume size listed in Synology documentation would still apply as a software limit rather than hardware one?