Don't ever make a decision on gear based on someone else's opinion. Do your research, read reviews, and then decide. In my opinion, yes, it is a fine setup to play recball or tourneys with. Depending on what league you may play though, they may not allow it (example: Most leagues ban the color yellow on your gear because typically that fill is used for paint).
Nice setup, but you could always keep upgrading as you obtain more cash and have an even better setup. A marker is a marker, man. Don't let anyone tell you that their Ego or DM is "so much better than your Invert Mini". As long as it shoots 285 FPS consistently, and is well maintained, a marker is as good as the next.
I'd pick up a used 4500psi tank instead of a steel tank though. Minis are great guns and with a boss or eigenbolt they shoot that much better. Also preference, but I like lurker eigenbarrels over CP barrels and they are cheaper.
You have to tune the marker after the new bolt is in correct?
You almost certainly have to. Tuning on a mini/axe is super easy and I never mess with the dwell. http://www.pbnation.com/showthread.php?t=3761332 The lurker tuning guide is a few posts down, but I use the main guide, but start at the lurker recommended pressure.