Can't speak to the sniper lite, but have had the mxb 320 for about 3 years. Have had no trouble in limited use. They recommend changing the string about every 100 shots and mine is due since the double serving is starting to pucker where the cocking hooks grab it.
This xbow if fairly quiet, very accurate, and easy enough to cock that my slight built then 9 year old Grandson cocked it with ease last fall.
I think the sniper lite uses a different cableing system than the 320 and is easier to keep in tune.