I have the Sony SCD1 and have also considering the Transport/DAC equation for Redbook. Here's what I've learned in a nut shell:
Nothing, short of the very best vinyl setup can touch
SACD -- buy the Sony for that reason alone. As for a transport doing Redbook, the big Sony is excellent, but there are others out there that are equally as good, perhaps better. After hearing some of the best (sorry haven't heard the ML 37 but have heard the 360s and was impressed)I'd rank the Sony up there with other $3-5K transports -- still, I think mine could still benefit from a DAC for Redbook. Trouble is, the DAC equation is changing very quickly, as more highend manufacturers take into account SACD, HDCD, etc that I'm not quite sure where my listening is going. I'm almost glad I'm not budgeted for this yet, as i don't really want to make a decision until after the CES show next year, when I can really get a sense of where the market is going and what sounds best.
More specifically, its difficult to answer your question, without considering what the Levinson or Sony will be paired with. To satisfy yourself, you're going to have to audition both. (I think the transports in your price range are all good, it's the post transport processing that will have the greatest effect on what you hear.) If you are considering the ML 360s then I think the ML 37 would be your best choice. But I'd still buy a Sony in additon to that (you can pick the SCD1 up in the low $3K range on Audiogon or eBay.
There's going to be a lot of shaking out in the DAC/SACD/CD transport/DVD-A market, especially with the (vastly inferior) multichannel stuff confusing the market even more so as manufacturers look for "numbers" and new markets by going into the high end?? multichannel market as they chase all those consumers with 5 speakers.
Be patient, and since you've narrowed your choice to two, listen to both. And why not contact Levinson to see what they are planning to do with SACD? My gut feeling is that within in 12 months, we'll many more high end solutions to SACD -- a Levinson 37SACD/360sacd?? -- I can only dream.