Some XTPs are a real money saver, especially if you buy the 100ct boxes. But for the most part, XTPs and GDHP/Deep Curls are pretty close in price, a couple of bucks difference. For a bonded bullet, I think it's worth it to get the Deep Curls.
Re the sabots, I have for the most part only used Harvesters. I have found that the sabot probably makes the most differernce in accuracy. For the 300gr .452 bullets, the long blacks give me the best groups, but are a true b!tch to load in my Omega X7. For the 250gr .452s, the short blacks seem to work the best. For the 240gr .429s, the green crushed ribs do the trick. I think Sabotloader is right in that there is no real way to avoid trying all the different sabots out there to find out what your ML works best with.