That question is entirely up to you. I don't have much to say regarding the Thunder Tiger Engine, I can say by being involved and attending many ,many fun flies, the OS105 is going to be your most popular and best choice in my opinion. I think when it comes to a monetary savings, I can appreciate your wanting to save money, but when it comes to these machines, you will be rewarded by spending that extra money on an OS105. It truly is a well balanced engine. I have run all the other brands and honestly I am very pleased with the OS product line. The N7 was designed to run the other engines you see, however the OS really compliments the N7, it is a happy marriage. For all engines in regards to how long it will last, is based entirely on how well you maintaine it (tune it) and how you store it between flights. It even comes down to the fuel you burn, I run Cool Power and have never had an issue, I also enjoy my Helis meaning I fly them hard, but keeping in mind I go the extra mile in taking care of them. Best of luck in your decision. I can only speak from experience, but fact being If the Designer of the Heli flies a OS105 in his bird. Decision should be simple
And also regarding the Total Time or hours in service, one of our Team Members just put 30 gallons through his OS105 before he decided to replace the Bearings. And he abuses his Heli, great pilot and flies hard.
Best Regards,
Kevin