The Micro ITR is the one that I use and love;http://www.penguinmagic.com/p/S3831
when comparing it to the Boss, many people tend to go with the Boss for 2 reasons;
1. The Boss is smaller
2. The Boss clips on instead of having to be pinned in like the Micro ITR.
The Micro ITR isnt' very large, but it is about twice as long as the Boss. If you can get past that and the fact that it has to be pinned in, you'll have a GREAT ITR. The upside that the Micro has over the Boss is that you can get a longer length of thread out of it...meaning you have more freedom to move further away from the item that you're hooked up to.
Another option is an electronic ITR such as the Spider Pen;http://www.penguinmagic.com/p/946
With the spider pen, you can walk up to about 20 feet from the object you're floating and still retain the support you need from the thread. This is UNHEARD Of with the other reels. This is made possible by the battery operated motor hidden inside of the pen. Since it's hidden in a pen, the reel is perfectly camouflaged. All you have to do is clip it in your shirt or coat pocket, and you're ready to go! The only problem many people fall victim to with the spider pen is the dead battery. This happens usually when you forget to turn off the motor, which will run the batter dead when not in use. If this happens, when you pull on the thread, it just goes EVERYWHERE and then you'll have to replace the thread spool before your next performance. BTW. The spider pen has a secret compartment for storing an extra thread spool.
I've recently been looking into the Titan ITR (Alpha size):http://www.penguinmagic.com/p/S13297
I'm very impressed with the video for this ITR and the fact that it's strong enough to hold up a deck of cards...in a box...that's very intersting.
Hope this was of some help to you!