Nitro,
You seem to be a knowledgeable IT-type trader. I believe the X-trader advantage is not only in its software per-se, but also in their TT feed, which is far superior to IB. Not only is it tick by tick, so that (if your machine is fast enough) you should catch every tick of the market, but it is also lightening fast. This Wednesday, the markets were about as erratic as I've seen them, flying all over the place. I had 5 MD-trader (that's the X-trader DOM) windows open (as I always do), and it was flawless, not missing a tick and never falling behind.
As a platform, X-trader may not have a lot of bells and whistles, but it is ROCK SOLID. I have been using X-trader for 2 or 3 years now. I currently trade between 1,000-2,000 contracts per month. And I have NEVER had a software based issue. Perhaps X-trader screws up, but I have never seen it happen. No questionable fills, strange crashes, nothing. For a 1-lot trader starting out, the transaction-based fees these firms are offering are, IMHO, a STEAL. (They're actually $0.05 cheaper than IB per rt, for a platform that is vastly superior. Edit: I guess with unbundled pricing, IB would come in $0.02 cheaper.)
I'm not knocking IB -- if you require equities, forex, and all the other exotic stuff they offer, I imagine they are the best choice.
But if someone is looking to learn how to trade e-minis, currency futures, bonds, DAX, or whatever, I can't imagine why he wouldn't opt for X-trader over IB.
As far as shelling out $500-$700 for the platform, remember this: At that price (I pay $700) I believe you are getting a commission rate that is far cheaper than IB. For instance, say I do 1,500 rt per month. At IB, I believe I would be paying $3.62. At my current firm, I'm paying $3.00. With 1,500 rt I'm actually saving myself about $150 / month after paying my platform fee. At 2,000 / month, I'd be saving about $500. At 5,000 / month, I'd be saving about $2,300! You get my point.
Put X-trader side by side with your favourite IB front end some time (especially when the markets are moving fast) and tell me if you see the difference. (I don't mean this as a challenge -- I'm truly curious.)