-Too far forward
-maintenance (for lazy people)
The Smart Parts Ion I have only had for a few weeks, but I've used my friend's before many times. They are great guns. It's hard to believe that now these cost 165 dollars stock. Here's the good and the bad:
THE GOOD: This gun has a great stock board. Dwell and ROFD (rate of fire delay) can be set to any rof speed from 9-17bps. It is legal in many tournaments, has a decent stock barrel, an okay trigger, (you have to set it to your preference) a quiet bolt with little kick, it's cool looking, fast, extremely inexpensive for its quality, and has the best customizability of any gun I've ever seen.
THE BAD: Stock feedneck isn't even usable, ASA comes out the back too far, making it uncomfortable to hold without a drop-forward, and the duckbill ASA's threads are tricky... you need to be gentle when screwing the tank in and out. You need a new feedneck right as you get it so you end up really spending around 200 dollars for a 165 dollar gun. Still not horrible though... Some say the power button is bad but it really isn't. Just push a little harder when turning the gun on and off.
Great gun. Absolutely amazing for the price. Smart Parts really did a good job. I love my ion and so do several of my friends. Nothing is perfect, but for $165, you can't beat it. 10 all the way.
The stock board is decent but definitely not great. The trigger pull reading code is awful cause pauses and skips while shooting and generally limiting your ROF. There's no way you can really fine tune the gun with the stock either. It'll do the job but nothing more. As for customizing it well it can't match that of the cocker or Mag.