I have ProChron-Plus. I have had it for ten years and it is the best working machine that I have seen. I have used it side by side with the Oehler and the Pact. I also had a Shooting Chrony. There is nothing wrong with the Oehler and I wouldn't turn one down. Nor would I trade mine for one. Sometimes regardless of price I find a fine product that I will stick with. There are newer machines and ones that may do more things than my ProChrono but every darn day in any light under any sky condition, It work perfectly. If this one ever gives out, I will buy another as much like it as they have. To me nothing else would be an upgrade. Good luck with your purchase.