Remote collar as in shock collar? So you tell the dog to sit, and if it doesn't you shock it? Not my cup of tea, to say the least. This is an extreme example of compulsion-based training (the typical example is 'leash pop' training). You may find that your Boxer responds better to training which allows it to think and learn, rather than causes it to work to avoid pain or discomfort; operant training, or "clicker training", seems ideally suited for an intelligent, independent thinker like the Boxer. There are a small handful of trainers who can safely and effectively use a shock collar without creating a great deal of fallout - but they in general use it in very specific situations, and as a last resort, not a first.
Oh - I see that "Sit Means Sit" is a franchise training operation as well as a shock collar brand. You need to do a lot of research with franchise training - some are good, some are horrible, even within the same company. Observe a variety of classes at the facility before making the decision. Again, consider less-severe training techniques that help you build a relationship with your dog and have fewer chances for long-term unintended consequences. (Also, while they claim they collars only give a "touch" to the dog, in order for the collar to work it must be aversive - something the dog will work to avoid - which means it must be unpleasant at best; for Boxers, which are often quite stoic, the "touch" may need to be uncomfortable or downright painful before it has any effect - it depends on the individual dog, of course.)
For a complete 180 on training methods, read the Training Articles at http://www.clickersolutions.com I have not done shock collar training, but I have done choke-chain, jerk-and-praise training; in my experience, dogs learn faster and are more willing to train with a clicker.