Ive got a soft spot for the 52cal and i personally really like the 52x458 sabots. The 475s are fine too but i can't find affordable bullets that i like as much. The 325gr XTP is one of the better "cheap" .475 ive found. They are not very cheap though compared to the .458s. There are tons of bullets in .458 costing from $40/100 to $2 each. Many of them perform very well at ML speeds also.

The Lehigh 275gr, Barnes 300gr SOCOM and Hornady 325gr FTX have all shot well in mine with upto 130gr of BH209. Hornady also offers a .458-250gr Monoflex that may be worth a try for those that don't need/want to shoot the heavier bullets. Its a "premium" class monolithic bullet but it can be found for less money than Barnes.