I can only give you second hand information on Ameriflight from FOs I've flown with. None of them said anything bad about them. Yeah, it's hard flying and not for the whimps, but you get good experience as well.
I came from a background like yours and got my ME 135 time flying for a similar outfit. Was the equipment top notch? No, but it was not bad. Was the pay great? No, but having owned my own airplane I know the owners had very thin margins. Did they treat me well? Yes. Did they push me a little? Yes, but if I said it was below minimums, they backed me up.
It is a great way to get single pilot 135 time flying approaches to minimums on a regular basis. No matter which route you take next, it will help you in the long run. I was in the 160th prior to my single pilot 135 time, and the only things tougher were NVG approaches in the desert and combat flying. Even landing on a ship at night was easier... at least there I had a good radar and stormscope; also had some one else in the other seat to back me up.
As I've heard before and told others, with this kind of flying you will either get very good at flying IFR, scare yourself out of flying, or kill yourself in the process. Good luck. And keep the dirty side down and the sunny side up.