The cone angle to worry about is with your telescope and its vixen bar. You will find adjustment screws on the bar perhaps to use to adjust it. In practice if the scope is bolted directly to the vixen bar there should be very little cone angle. If the scope is in rings with three screw mounts then the cone could indeed be pretty terrible.
If you search the forum you will find a video Jerry posted regarding how to adjust cone angle.
If the telescope is mounted directly to the vixen, that is without adjustable ring mounts, the cone error will certainly not give you a problem if you SYNC anywhere near your dim deep space object.
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired