I will say, as far as steppers go... it is amazing what Selwyn did with them. If memory serves correct, his SS500-PDs used steppers and could hit about 20~25K @ about 5° if tuned by a pro.

Regardless... you could pick up a pair of cheap 15K galvos on ebay for about $70 and they would be WORLDS better than what you have. Then again, you would need software and DAC and all of that.... so, baby steps!