Tough call. Though I think the Mach 4 will still probably be serviceable and useful I, personally, would probably get a new bow...not necessarily because it is "better" but rather because a new bow has less of a chance of something wrong occurring with it.

I don't think you need to go with a $500 or $600 bow to get quality though. Even the "low price" bows of today are better than the "high price" bows were 6 or 7 years ago.

I think there are several bow combos out there, including from PSE, that would cost you less than $400 to fully equip and that will suit you as well as an $800 setup...from a practical perspective.

Hope this helps.