Well 3D fliers tend to be pretty power-aware and I think most are happy to keep using an engine so long as it provides acceptable performance (pull-out from a hover, etc) and reliability.

My 200+ hour TT46 meets all the criteria (including one-flick starts) so I don't consider it "worn-out".

Anyone who's *really* worried about that 10% of power that has been lost is probably really competition-oriented so likely wouldn't be using a sport engine like the TT anyway -- they'd be spending twice as much on a Webra or whatever.

And as for the ABN/ABC issue -- I've got a GMS32 which has a true ABC liner and it's worn out (ie: hard-starting, low on compression and power) after less than 5 hours running. So, a chrome liner doesn't always mean a longer-lived engine -- there's a whole lot more to engine longevity than just the metals used.

Both engines have been run on exactly the same fuel (10% nitro with 20% lube of an 80/20 synth/castor blend).