Well, growing up with Lunar, which had a very high quality localization and release, I have good expectations if Vic Ireland is involved.
I honestly think the most that could happen is some funny
woolseyisms added into the dialog (Working Designs was famous for their Woolseyisms) and toning some of the loli aspects by maybe aging up some characters.
Working Designs also treated their customers really well. And their translations were a labor of love. However, they only released really lavish deluxe packages of their games. That's how they made their profits. All the games were more expensive, but to make up for it it came with awesome bonus items. They were doing great until the early naughties, when SCEA forced them to release games with "normal" packaging. That's actually what led to their downfall.
Here's the box for Lunar 2: Eternal Blue that I got, it shows all the nice things that they put with the game:
http://www.youtube.com/watch?v=PjzyzTj8LnsIt came with a leather-bound book with lyrics to vocal songs in both English and a very literal translation of the Japanese lyrics, artwork, interviews with the creators, a mini-walkthrough, behind the scenes, as well as character standees, a poster, and a replica of Lucia's pendant in-game. Keep in mind that Working Designs themselves made the pendant. There was a similar pendant sold in select stores in Akiba, but it was much, much smaller.
If we can expect that kind of quality with the localization of iDOLM@STER, this is a very, very good thing. They probably won't go all out with the bonus items due to costs for such things these days, but I've played through Lunar 2 and the translation is top-notch even though it's not faithful. In the Japanese version, you'd have the townspeople saying generic tidbits, but in the English version WD gave the NPCs personalities of their own just with their dialog. But the main story itself stayed exactly the same. However, iDOLM@STER is based entirely on dialog, so they won't have to change things like the NPCs in Lunar. They'll just treat it the same as the dialog of the main characters, means the same thing but maybe add a bit more flavor.
And as I said, a lot of games these days have the option for Japanese audio, I know the Atelier games do. It shouldn't be too much of a problem.
I mean, look at Hetalia. The Funimation dub changes the entire thing to a gag dub with more American sounding jokes, but at the end of the day you can watch it in Japanese with English subtitles on that same DVD.
Also worth mentioning that freaking OTOMEDIUS somehow managed to make it to the states complete with body pillows, but something with a much broader appeal like iDOLM@STER hasn't.
And last but not least:
Nobody's forcing anyone to buy it. Most of us have imported a game or two, we can always play the Japanese version and have the same experience. But the English version could be a brand new, fresh experience.
Also. JENNY STIGILE JENNY STIGILE JENNY STIGILE.
I'd fund the kickstarter if it meant iDOLM@STER in English. Of course, my expectations are WAY too high since this is Gaijin Works, not Working Designs, and they can't afford to go all out these days I bet, but I imagine the same spirit.
Also, WD was very good with dubbing songs. In Lunar 1 they made up the lyrics, I admit, but in Lunar 2 the lyrics are slightly different than the Japanese but still carry the same message. I think as long as the song has the same message, any translation is fine. Here are the Lunar 2 songs they translated:
Also, here's a great example of a Japanese song dubbed into English working well, the first Rurouni Kenshin opening:
http://www.youtube.com/watch?v=UIcvHSUCiAsI honestly prefer it over the Japanese version...
However, I think it's very likely that the dialog will be dubbed in English but the songs will stay in Japanese. That's the attitude most anime translators have these days.