Chris,
I have been fortunate to play Belle Meade a few times since it re-opened and look forward to a round there later this week with Tiger Bernhardt.
The 3rd hole you mentioned no longer exists. The hole is now a straight-away par four with the green sited right of Richland Creek instead of across it. Routing of the 4th and 5th remain unchanged but the par three 6th now plays along side Richland Creek instead of crossing it as well. The new 6th green is in the proximate area of the old 7th tee with the new 7th tee was moved well left and across the creek to soften the dogleg. No need to challenge the big sycamore down the right side. The routing otherwise remains unchanged.
Given the work of RTJ and Gary Roger Baird at Belle Meade, I am not sure how much Ross remained before the entire course was plowed under by Rees Jones.
Generally, I find the course much more difficult. Many of the greens were pushed up considerably and are difficult to approach as they are generally table-top, lacking the front to back slope that I tend to (perhaps incorrectly) associate with Ross. Too, the back of the bunkers (the farthest side from the green) tend to be built up a little bit both internally and externally. The former yields many slightly downhill sand shots to elevated greens while the latter tends to profile the bunkers. One could say the back of the bunkers are slightly mounded.
I really like what was done with the 12th, which requires a mid-iron off a downhill lie to an uphill green. Rees moved the fairway near the green to the right with a ramp feeding left to the green around a deep fronting bunker. Classic stuff. Visually, the par three 10th, fully visible from the casual dining area upstairs in the clubhouse, has the orientation and bunkering of a Redan - including the short carry bunker. Unfortunately, not the playing characteristics - somewhat of a shame since a lot of dirt was moved anyway.
Notwithstanding Tom Doak's quick dismissal in The Confidential Guide, I think Belle Meade ocupies a tremendous piece of parkland property. Rees' work is basically a brand new golf course incorporating an existing routing, for the most part. The course retains a classical look and I would suspect is unique among Rees' portfolio.
Mike