When I apprenticed I learned hammer and chisel first, after I was failry proficient with H&C, then I was taught airgraving on GRS equipment but when it came time to buy I visited both GRS and Lindsay(I live about an equal distance from both) and I went with Lindsay Classic with foot control.
There were a couple of deciding factors for me, the first was the experience I had with running GRS equipment and the customer service that GRS had given the man I apprenticed under, he didn't give them a glowing review for the way they treated him. The second reason is cost...having run both I decided I would spend less money with Lindsay to get a single machine that does the same as a GRS machine with 3 separate hand pieces(you have to buy the extra hand pieces separate) and the Lindsay is portable(only requiring an air or co2 bottle, I've even run mine on argon at a show once) while the GRS requires both air and electricity to run(not as easily portable).
Have a quick look at the first video at this link. It is Steve Lindsay presenting it so I will grant any bias anyone wants to call but the comparison is stilll pretty plain.
http://www.airgraver.com/video.htmSteve Lindsay has treated me great every step of the way, from opening up his home/shop to me on a Sunday afternoon(the day before he had to leave for a show in New York) so I could come up and try his equipment(he walked me through the entire set-up while I was there) to the great customer service I have had. Like when I got a new puppy and she chewed up the air hoses from the foot control to the hand piece. I called him up and he sent me new hose no charge for hose or shipping. I know that hose is a cheap and small thing but that is really good cusotmer service to cover stuff like that when the customer admts it was clearly his fault.
I will add that while I learned how to hand sharpen graver blanks, it wasn't until I bought the Lindsay Templates that I really knew how much time I was wasting and how frustrating sharpeneing gravers was. It's never a bad thing to learn how to hand sharpen your tools but his templates will really spoil you for consistent repeateable sharpening in a fraction of the time it takes to do it by hand. Even if all you do is learn H&C I would still recommend the Templates for sharpening.
Hope this helps.