110 MB/s is the max a NAS can achieve without LACP in action. With LACP or with multiple systems it can do double as that in optimal conditions. With my managed switch, although it supports LACP, I couldn't enable it/make it work so the max speed was restricted to 110 MB/s.
Also pure network transfer speed by no means should be the only factor on which such servers should be rated. With free NAS you have zero support if something goes wrong, you have to set up the machine on your own (so have the knowledge to do this) etc. On the other hand as you said it will cost much less so it is up to the users to decide what they want.
In NAS servers like QNAP and Synology ones you also pay for the support and for the custom made/cooked software which offers great flexibility and makes life much easier. Also if something goes wrong and even if you experience a crash you will have proper support by them (in some cases I heard that remotely they even restored the RAID/data). Finally, if these companies were jokes they surely wouldn't have so many years in this area and would vanish from the start. On the contrary they are highly successful and this means a lot.