The myrm isn't terrible but it has several downsides;
Too slow a turn speed.
Presents too big a target.
Only one bank of it's secondaries is usefully alligned (otherwise the missiles all fly out of different holes, it's a bit difficult to maintain a steady stream of the only truly good dogfighting secondary; tempests).
The first primary bank (the dual bank) is too high to be effectively useful vs an equal skilled pilot turning at the same speed unless you're pulling up (which isn't actually very often vs joystick pilots, because it's naturally easier to dive, you can roll into it so you end up asif you're pulling up relative to them but it can take too long).
Other than that it's pretty ok, definitely not my dogfight ship of choice though, only /really/ useful with a morning star in the top bank.
Unless you're purely shooting down bombs or something, I rank subach right along with prom r btw :<
Perseus/Uly/Loki are very high skill requirement craft (ie; not great in rookie hands) but they tend to outperform all the others in the hands of someone who really knows how to use them.
Eri is the 2-4v2-4 fighter of choice.
The Mk2 is often used as support to the Eri (because Eri's are so dangerous they can't be ignored, which leaves the Mk2 to sit at range with MornS and secondary spam, not my fave tactic tho

)