You're not going to find any SACD player that has an onboard DAC and associated output stage that audibly bests the BDA-3.
The transport, as long as it's well made, like in virtually all products nowadays, will have ZERO affect on sound quality, despite what the manufacturers of expensive transports try to make you believe. If you mod your existing Oppo to be a "SACD transport", you are wasting your money. SACD's complexity is all in the processing, not in the reading of the disc. All a transport does is use a blu laser to read the spinning disc and output the digital bits. ANY decent player can do that perfectly.
That leaves the HDMI interface. What facts do you have that support the conclusion that HDMI is inherently noisy, or in any way inferior to any other digital interface? I'm not talking about listening to what "internet people" tell you, which is 90% garbage. FACTS.
My opinion, if you can't guess by now, is to not waste a dime and keep your current setup. You sound like you're afflicted with the well-known audiophile phenomenon of "upgradeitis", and will continue to spend ever more amounts of money chasing your tail in pursuit of audio nirvana. Want to spend some money to improve your system? Spend it on speakers (or setup, which is free), higher quality recordings, and improvements to your room acoustics. Those 3 things make PROFOUND differences. Differences in electronics are miniscule by comparison.