I would class them both as spool markers as oposed to knock open valve designs.
The ion could be considered a simplified matrix, the bolt and operation are near identical with the only real difference (apart from quality) being the ion solenoid is soley used to return the bolt, forward motion is caused by the spool being unballanced.
I personally think it's a superior design to both the matrix and shocker and really cannot see why smart parts haven't released a high end version built to the same standard (or hopefully better
![Roll Eyes :rolleyes: :rolleyes:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
) as the shocker.
Back to the original question. Take the ion with stage 5, with the added BOB ability why would anyone take a more complicated/unreliable design.
Most of the ion issues i've seen have been caused by having to dismantle the whole marker to lube the bolt, with the stage 5 that problems gone and you get the look of a quality marker.