I use a Remoska having been gifted one by my mother. I had always thought them a gimmick but they are not. They do everything they say they will with just one exception. I cannot get my roast vegetable to crisp up as good as in a conventional oven, and that's it. I love my cooking and I am a convert to them.
The halogen get very good reports and again I am led to believe will do all you ask of them and at a lower new cost. Drawbacks though are size, weight, possibility of damage and high wattage that means you are unable to use it on some sites.

If buying a Remoska new then the best place is Alza.
The standard 2L is perfect for 2 people, and the classic black lasts the test of time. The only choice to be made is window in the top or not. On the older models (which I prefer) steam condensing on the glass window and getting into the electrics was an issue at times, but in our 25yr old model (10yrs of summer and occasional home use) this has not happened. I did speak to an owner of the new style windowless model this summer and they missed the window, found that items at the top tended to burn and thought that the shape of the teflon base resulted in a smaller real capacity. They had difficulty fitting a small chicken in, something that we had also roasted in the past.

Buying 2nd hand would be the way to go. You could get a older design model allowing use of shallow teflon pan and dividers (new model does not have option of shallow pan), it is a lot cheaper and if you do not get on with it you could sell on for what you paid for it. I am keeping an eye out for a good 2nd hand one near me to buy as a spare. Best place to look is Gumtree.

Best of luck - Colin