If I were not reloading anyway, I'd stick with 223. The thing I like about 6x45 is it's such an easy case to make. No fireforming, trimming, donut removal or neck turning. All you do is size, load, and shoot. I do the same things with new and once fired brass in std cartridges so there are no extra steps involved in loading 6x45 v 5.56. To be sure, I don't like losing brass, but that's a personal problem.
As to bullets, the best shooting mag length load I've found so far is the 85gr. Sierra Game King right at 2.260. It's a traditional shape, loads to mag length, and shoots very well in my gun. I love the 87 V-max, but it wants a coal (approx 2.35) that won't fit in the mag so I only use it on the bobsled.