Well, there's two sides of the coin here regarding which sugar alcohol is best for ice cream. For the best
tasting ice cream, definitely maltitol. Maltitol is, by a landslide, the best tasting/most sugar-like sugar alcohol there is. It's also a no brainer 1 for 1 sub with sugar. In a perfect world, all us sugar free devotees could just switch to maltitol and that would be that. Unfortunately, maltitol has issues
It's laxating. Sensitivity varies from person to person, but for a pretty good chunk of the population, maltitol represents abdominal pain/porcelain throne time. Even if you're one of the lucky ones that can consume it without gastric repercussions, there's still glycemic impact to deal with. I don't always agree with Mendosa, but in this instance, he's on the money when he talks about the glycemic impact of sugar alcohols:
http://www.mendosa.com/netcarbs/
Bottom line, depending on the individual, maltitol can be high glycemic and/or laxating. Maltitol doesn't laxate me, but it gives me a major sugar rush. I don't measure my bg, but the feeling is quite pronounced. Maltitol syrup is even worse. I get a huge buzz and then crash viciously. Lactitol, on the other hand, tears my insides apart. Xylitol has a lot of devotees and is widely available, but unfortunately it's still in that potentially laxating/potentially bg spiking gray area. Isomalt- same deal. All sugar alcohols are potentially laxating/bg spiking... with the exception of erythritol. Because erythritol follows a different pathway through the body, it doesn't cause laxation or a rise in blood sugar. It's one of a kind in this way. It's expensive, unavailable locally, it crystallizes in a heartbeat and can have a 'cooling effect' if not handled properly, but you can serve it to company and not worry about sending someone to the bathroom and it's wicked low carb/low calorie/low GI. I don't use a great deal of it, but it holds a very honored place in my sweetener pantheon.
If this ice cream is only going to be for you and you're perfectly fine with any potential ramifications from the maltitol, then maltitol it shall be
A maltitol based ice cream should be pretty easy.
Polydextrose and erythritol make totally kick butt desserts, but they can get a little complicated/intimidating. If people are looking for the absolute best in sweetening with the fewest potential tradeoffs and are willing to put in the money, time and effort, polyd and erythritol are the direction that I point them in. For the less adventuresome, I stear those people towards ace k (Acesulfame K). Ace K, brand name Sweet One, improves the taste of splenda exponentially, is cheap and is relatively easy to find locally. It may be hard to imagine the taste of splenda being improved upon with the addition of other sweeteners, but once you give them a try, the difference is night and day- especially with bitter items like unsweetened chocolate or frozen applications.
Right now, my sweetener blend of choice contains liquid splenda, erythritol, ace k and polyd. There's some sweeteners on the horizon that might improve upon it (tagatose could be promising), but for the moment, I believe that there is nothing better for recreating the taste and the texture of sugar. It's in a class by itself.
Btw, what are you're feelings about fructose? I'm very anti-fructose because of the long term health issues associated with it. This being said, it amplifies sweetness when frozen and works wonderfully in ice cream in very small amounts. The key words being 'very small amounts.' If you're open to it, I'd recommend obtaining some for the sole purpose of ice cream making.
