I'll take an RB250 over a 300 any day. There are some very effective yet inexpensive mods you can do later. I second the suggestion to go with a VPI HW-19 Jr. Great tables, and they're quite easy to upgrade as your funds allow (and believe me, you'll be upgrading. No one escapes the sickness ;) After a while you'll have turned it into an HW-19 MkIV that will play with some of the big boys! VPI does the low-end well in my experience.
I haven't much experience with SACD, but you'll have no problem exceeding your Redbook performance.
I haven't much experience with SACD, but you'll have no problem exceeding your Redbook performance.