I would be highly skeptical of any company that claims a "near perfect summit success record." In addition, you will save tons of money by waiting until you arrive in Tanzania to book the climb. (US$2,180 for a 7-day Machame route is ridiculously high.) I would definitely recommend that you go to Moshi to book the climb and avoid the hassles of Arusha.

Have a look at the Kilimanjaro Porters Assistance Project for very important information about choosing a company that treats porters humanely:
http://www.kiliporters.org/index.php