I have a 2011 C5 Bullet. Its one of 10 imported into my country for that year.
Runs great for what it is designed for. They were/are not built for blasting down the highway, but are a very nice handling bike for day to day secondary / backroads riding. Peg dragging it on sweepies is still fun. just remember that the pegs are solid mount, unfolding affairs and lead to making an excellent pivot point for a short journey to the nearby ditch.
The newer unit construction engines with fuel injection are fantastic, coming with hydraulic lifters and keihne injection system.
The stock spark plug that the bike is shipped with is a wonderful item to put in a drawer. There are better plugs to usen that smoothn out the idle and stumbles.
Over 22,000 km of fun. No breakdowns. No bolts or bits flung off.
Cant say much for the older iron barrel or lean burn engines as I've never owned one.
The Royal Enfield USA website is an excellent resource and a great bunch of blokes. Much like here.
yeh bullet meri jaan