1. Opinions vary but to me the SR-007 Mk1 is a bit soft, the SR-007 Mk2 with port mod is close to neutral and the SR-009 is on the bright side.
3. The advantage of Blu-Tank over a fitted piece of plastic is that the Blu-Tak can mold to any small irregularities and form an air-tight seal, whereas there may be some small gaps with a printed plastic piece. As the whole idea of the port mod is to seal off the port completely, Blu-Tak should do a better job.