There are huge differences between a full blown HD rig and any Pro Tools LE setup. The first most obvious difference is price. Second, there is better DSP (HD Accell). Third there is TDM. All of those things drastically change the way Pro Tools is used and how well it operates. There is also the fact that LE systems have stricit limitations as to track count etc... If the way you work meets the limitations of Pro Tools LE, there is no reason why you couldn't use an LE system succesfully. Not to mention it is easier to transport a project form LE to HD than it is from Nuendo (which is my application of choice). The hardware limitations of Pro Tools is changing as well. You can now buy Apogee conversion for HD rigs and run them without also having to buy proprietary Digidesign hardware. A full blown HD rig is still pretty well unmatched as far as features, speed, usability, and stability goes, but other companies are making some nice headway in breaking into the professional studio environment and are quickly closing those gaps. I personally could not use an LE rig in my studio, but can't afford an HD rig without having to make some huge sacrifices that would in the end have more of a negative impact on my studio. Therefore I choose to use Nuendo which (along with Digital Performer on a mac) is really the next best thing to the professional acceptance of Pro Tools. However, if my budget were to allow me to comfortably get into Pro Tools HD without having to make too many compromises, business savvy says it would be well worth it. In this day and age, luckily, Pro Tools is not a necessity for home users. There are many viable options that are very powerful and very capable. However, at this time, there really isn't anything that can compete with Pro Tools. It's kind of like an SSL console. They are excellent desks, but there is always something nicer out there. However, not even a Neve console meets the demand, usability, acceptance, and familiarity of an SSL. probably why SSL is the console of choice for most every major studio on the market. All the tried and true engineers and producers know how to use them and what to expect.