Realistic perspective  

I can only speak from AMC obesrvations:

1) You'll be paid well due to the per diem, travel OT, etc. but remember that your float job will probably pay way more than any assigned base you hope to "settle down to".  Hard to take that pay cut for some.

2) You could get assigned a helicopter type that is not the type for the base you're hoping to "settle down at" (since as a pool pilot you'll get preference for positions that open as a benefit of enduring the suck of being a pool pilot).  They have no guarantee to let you switch later.

3) KNOW THIS: You'll work a 9/5; not a 7/7 as every HAA company makes you travel on your off days.  Consider how far you live from a major airport, if it's a regional, etc. time to get a rental/turn-in rental, etc. in your choice to do this a those hours add up; but you are paid OT during ALL of that time at least.

4) Unless your're a 58D guy or have time single-pilot in the 72 you're going to be overwhelmed; ESPECIALLY if you flew the 47.  Every EMS bird is small and squirrely requiring you to remember how to really fly a helicopter.  Learning a G430, autopilot upper modes, etc. is NOT intuitive (and I was at Rucker when we transitioned MANY guys who were current but hadn't flown those things and they sucked (and had plenty of slow instruction and hours to work on it). Also, the majority of HAA use Airbus type helicopters which are a huge mind-F from the mighty Bell, Boeing, Sikorsky fleet of the military... just learning their nuances and poorly translated pubs is PAINFUL.  

If you think you'll just wing it during the short training week given at every HAA you'll be in for a big surprise.  If you don't get some sim or actual helicopter time in you could be shooting yourself in the foot.  Even some time in a buddy's plane with a Garmin to get used to radios, the GPS, etc. could help.  There will not be a PC to "fly with" to learn the ropes.  

5) You could be assigned at a sleepy community base one or one in downtown city within Class B airspace... you don't know and things could be VERY overwhelming.  

6) You're not used to having crewchiefs/PAX be able to question your judgement the way medcrew do in HAA.  Their perception and feelings trump your experience (and dated experience at that).  It will be painful man.  

I'll probably think of more.  Many of the other posts here are spot on, actually, so take them to heart.  HAA is so hard up someone will probably take you, though, so if you're just itching to try you'll probably get a shot.  

I would recommend using your GI Bill to get your FW ratings and trying that route.  You'll get training to be up to speed and will ultimately have a better quality of life in the end.  

Or, stick with whatever staff officer experience you've gained and find a job that will pay WAY better than HAA or initial FW job and just fly airplanes for fun on the weekends because you can afford it.