You state "Aftermarket sensors are not generally reliable". However, the aftermarket sensors most readily available are made by BERU who supply BMW with essentially the same parts. Why should the non-BMW badged versions not be reliable?
The TPM system was changed in September 2009 on E9xs and the following year on some other models (e.g. X5). Although the frequency remained the same, apparently the new and old systems are not compatible. How does that impact this device?