When it comes to bikes I say go ahead and buy one. If it doesn't work out you can resell but still had the opportunity to ride.

Suspension is great for rolling over curbs and logs, but doesn't do a whole lot of good on bunches of small bumps or broken concrete. High frequency chop I call it. Full suspension would help with the deep pot holes, but you shouldn't be riding into the deep ones anyway.

Seatpost stems are another thing that I've never personally understood. I can see where it would be handy for the occasional surprise bump, but for the most part I have to wonder why people are riding full weight on the saddle through the rough? Just lift a bit and loosen your grip, let the bike take the vibration.

You do realize the cushier you make the suspension the more effort it will take to ride? Bigger tires really only help if they aren't inflated rock hard.