I don't think it does, since in the modern era, the RATs have had far less opportunities than Republicans to name SCOTUS judges. They haven't even named a CJ in 60 years. If the RATs president were appointed as many judges as the GOP, there'd be a far great opportunity for slip-ups. It's:
Obama - 2
Clinton - 2
Carter - 0
Johnson - 2
JFK - 2
vs.
GWB - 2 (1 CJ)
GHWB - 2
Reagan - 4 (1 CJ)
Ford - 1
Nixon - 4 (1 CJ)
Eisenhower - 5
If the RATs had 3 times as many judges, I think they'd be bound to have far more slip-ups than Byron White. Plus, alot of the GOP duds didn't become defacto Dems (Souter is only example of that since the mid 70s), but they were right-of-center judges who voted conservative far less than expected (O'Connor, etc.)
I think the biggest problem is the "evolving justice" issue. You're right, Roberts was a pretty reliable conservative for the last 6 years, but if this most recent session is a sign of things to come, we're in trouble. We can't afford to have Roberts go wobbly on us. And I've never seen a RAT justice go wobbly or "evolve" into a conservative. White was a fairly moderate right-of-center justice throughout his tenure on the court. Blackmun, on the other hand, started out as a "Minnesota twin" of Warren Burger, and ended up as the court's most liberal member when he retired in 1994.
One thing I will say is a bad factor on how to choose a judge: the concept that it doesn't matter what their personal views or record is, as long as their "judicial philosophy" is a "strict constructionist" or "originalist" or whatever they're calling it now (I never heard of this term "originalist" until a bunch of freepers started demanding GWB appoint one). Most of the "strict constructionists" that Nixon appointed came back to bite him in the butt big time. I want a lifelong, principled CONSERVATIVE, not some judge whose personal views are unknown but assures the President he is a "strict constructionists" Hell, I think Souter promised Bush that too. Anyone would say that if it meant a lifetime slot on SCOTUS.
I know that Republican presidents have made a lot more SCOTUS appointments than have Democrat presidents in recent decades, which is why I specifically included a *percentage* of appopintments since 1952 that have been disappointing for each party. Since 1952, Republican presidents have appointed 18 Supreme Court Justices, and at least half of them ended up being a lot more liberal than the president suspected: Warren (Ike), Brennan (Ike), Stewart (Ike), Blackmun (Nixon), Powell (Nixon), Stevens (Ford), O’Connor (Reagan), Kennedy (Reagan) and Souter (GHW Bush). During the same period, Democrat presidents have appointed 8 Supreme Court Justices, and only 1 of them ended up being more conservative than the president suspected (Byron White, appointed by JFK in 1962). So even if we consider Justice Roberts not to be a disappointment (I hope yesterday’s ruling was an aberration), 50% of GOP SCOTUS appointments over the past 60 years have been disappointing to the party, while only 12.5% of Democrat appointments have been disappointing to Democrats.50% is a heck of a lot more than 12.5%.