I have one and like it - it will trim to very consistent lengths once you are used to setting it up and using it.
The shell holders for some (not all) calibers specify different holders for new and used cases because the fired cases have expanded slightly and are a little too large in diameter for the "new" or unfired holder. The first few calibers that I loaded for, I bought both, but I generally get my brass by reloading once fired factory ammo or buying once fired, so I really do not need the " new" holders. Unfired brass often will not require trimming until after one or two firings, so the " new" holder, for me at least, is not used much if at all.