Deer are not tough, I have used the 200SW exclusively for years and taken deer from 20 to 338 yards and everywhere in between. The bullet was plenty. There is nothing wrong with the 300gr at all but you certainly don't NEED a heavier bullet.

Personally I think 200gr is a good weight for a .40cal bullet, 240-250 for a .44-.45 bullet for deer, and you can use heavier if you want in those calibers. I've actually switched to the 325gr .458 FTX this year for more long range energy.

As for the easy glides, shoot the regulars first. If you have to hammer them down the bore than get the easy glides. I have yet to hear anyone report that the easy glides were accurate in a gun that the regular sabots loaded ok.