The lack of upstream G.INP in Vigor 130 modem4 firmware results in higher latency due to interleaving. With modem7 DSL firmware, the actual downstream data rate is in some cases noticably lower than the attainable rate, despite the DSLAM being configured to allow a higher rate. This particular issue also affected other VR9 modems (including Fritzboxes), but it was fixed by newer DSL firmware. Unfortunately Draytek never released a newer version for their VR9-based modems.
Note that my recommendation is specifically against the Vigor 130 in combination with a DSL line operated by DTAG. It might well perform better in other networks (especially if G.INP is not used). Newer devices like the Vigor 165 also use more recent DSL firmware, so they should work much better in general.
Personally I would still try to avoid Draytek devices if possible (the configuration interface requiring reboots for everything is quite annoying, there is some weird/buggy behaviour in the command line interface, and there are hints that their DrayOS might contain Linux code in violation of GPL). But I understand that local availability of alternatives might be an issue.
Personally, I use a Fritzbox 7520 with OpenWrt. Unfortunately, the modem in some of these devices (which cannot be distinguished externally) requires an additional patch that appears unlikely to get accepted into OpenWrt.
A good choice for a modem that just works here in Germany would be a cheap used Speedport or Digitalisierungsbox that supports bridge mode. Depending on the particular model, these only offer limited diagnostic possibilities, though.