9 years later..
Ok sorry for reviving this thread, but there are unanswered questions present, which I could provide an answer for. I got the M44G on my TTX and on the Technics 1210s. Never tried the M447, but compared to an Ortofon DJ cartridge (the blue one with orange print).
Shure M44G vs M447
From my understanding the main difference of the M44G and M447 is the output of 9mV (Gs) vs 11mV (7s). The other main difference is the amount of weight you have to put on each cartridge in order for it to be skip-resistance. M44G are supposed to hold track with 3 grams (DJ setting in the Shure manual) and the M447 needs only 1.5 grams. I can atest that you need at least 2.5 grams on the M44G IF you mount it normally. If you use the "unorthodox" angled method as it is described in the Shure manual, 2g may be enough, because the tracking forces to left and right, when scratching should be less in that aligned setup, at least that's what I'm thinking.
Ortofon and Audio Technicas
I tried the Ortofon DJ and they are very usable for scratching, too, however I always felt the record wear on those was higher, because the needle is hard-mounted into the cartridge whereas with the Shures, it isn't. The Ortofon Pro (elliptic) I tried to, and it skips like heck when scratching. I also tried the Stanton 680 and the Audio Technica AT91 MM (spherical), both have a very sweet, clear sound, but will skip more often than the Shure's.
The cartridges on different Turntables
Last, but not least, the Numark's are heavy-build, high-quality turntables, which I would recommend in an instant, however they have a lighter construction where it counts: On the tonearm. I tested Numark TTX USB and the Stanton 150 ST-150, which is
an absolute tank and a very nice Turntable indeed. However, again the tonearm mount is flimsy compared to the 1210. Only the Technics 1210 offers a tonearm mount that is able to create absolut confidence. I doubt that we will ever see such a tonearm again, at least for under 2000 USD/EUR. And exactly this is the reason why the Shure's do hold a tad better on a Technics. So you can use 0.5g less on a Technics. Having said that, learning to scratch on a Technics is harder, because the drive is really weak compared to latest models from other manufacturers.
Conclusion
The M44G seem to me the better overall deal than the M447 in terms of sound quality and scratchability. I am switching music styles often. However if you are a pure scratch-head, the M447 will offer less record wear, because it needs less weight. The AT91 or AT95 for only 20 bucks are the best bang for buck if you want to digitalize your records. They are worth a try.