Roxio's Drag2Disc does not support UDF 2.50, so you have to exclude this one if you want to exchange discs with Drag2Disk. Also, latest Drag2Disc version introduces a priorietary way of writing "UDF" (strictly reading the spec, the newest D2D discs are not UDF discs) which InCD will support in its next (free) web update.
Absence of DRT-DM does not limit the UDF selection range. Absence of MRW, except for DVD-RAM, means no hardware defect management, so only UDF 1.50 or higher is possible (not UDF 1.02). As explained in the links given in this thread, UDF 1.50 is the first UDF revision to allow software defect management.
The InCD defaults and UDF revision recommendations are based on specifications from the various media types supported by InCD. For instance we recommend UDF 1.02 for MRW according to the MRW spec, or UDF 2.00 for DVD-RW according to the -RW spec.
DVD+RW has hardware-level defect management only with MRW. Some DVD-RW recorders, such as Pioneer devices, have DRT-DM support, which is an hardware and software collaboration for defect management. So it is difficult to say if + or - is 'superior' for packet-writing. Well, DVD-RAM has built-in defect management, always, so take DVD-RAM