Be aware that the upgrade just adds a micrometer adjustment to their standard seating die. It does not give it the abilities of their competition seating die to align bullets. I got a four-fold decrease in runout in .30-06 when I went from a standard Redding seater to their Competition Seating Die (back around 1990-92 period).
When German Salazar's Rifleman's Journal was still open to the public, he had a test of five different seating dies. The Redding Competition Seater was the only one he found could actually reduce runout to less than the neck runout in a case. It also produced the tightest groups, outperforming even the Wilson arbor press seating dies that the AccurateShooter/6mmBR site extols. It blew past a Vicker's competition seater, and one other that I've forgotten, both in terms of measured runout and results on the paper.
Unfortunately, Salazar did not include the Forster Ultimate seater in his test. It used the original sliding case alignment sleeve patent, a design Forster bought after it had changed hands two or three times, IIRC. That patent expired in 1989, and Redding designed a copy and then added a floating seating stem to it and got a new patent issued that same year to cover the addition, claiming it would align a bullet under one set of circumstances in which the original design would not. I don't actually know if that circumstance shows up often enough to matter so I don't know how the Forster and Redding tools compare in the final analysis.
In the Salazar tests the RCBS standard seating die came in second. Some time ago, John Feamster found the RCBS competition seater to be inferior in produced runout to their standard RCBS seater (Precision Shooting Reloading Guide, 1995). The standard RCBS seating ram is on a long, thin threaded adjustment rod, and apparently that flexes enough to act like a floating stem. Feamster got less runout from it than any other dies he tried, but he only tried the Wilson and the RCBS standard and RCBS Competition dies, IIRC.
I know that's not how it's supposed to be, but it seems to be that's how it is. The Redding seater is by far the most expensive. I haven't tried the Forster simply because I tried the Redding first and was so impressed with it that I've just bitten the bullet and gotten them for all my rifle calibers ever since.
Yet another option for seating exists. A limitation for seating dies is that they have to work to straighten the bullet, which most folks just set on top of the sized case mouth and guide with their fingers until it starts into the press. You can prevent most runout using any seating die if the bullet starts into the die already straightened. This can be accomplished using e Lyman M die. These dies are neck expanders that put a small expanded step in the case neck at the mouth. The bullet sets into the step and thus starts into the case straight, regardless of whose seating die you use. This greatly reduces the chance of producing high bullet runout.
Regarding the Redding lock rings, they have a small piece of lead or other soft alloy at the end of the screw that provides very positive grip. They won't hurt the threads unless that little piece falls out and you drive the adjustment screw in without it. I've had that happen. Since I use a Forster Co-ax press, at one point I just bought a bag full of their cross-bolt type lock rings and use those. RCBS has them that do the same. If you prefer one with flats for a wrench, the Hornady design is what you want. The ⅞-14 standard die threads make all lock rings interchangeable. Just get what you want.
Regarding Redding or any other expander design, steel expanders need inside neck lube, regardless of the type. However, the carbide expanders, which are available for Redding, Lyman, and RCBS, greatly reduce the friction. I've found, using a Redding sizing die I have, that changing to the carbide PLUS using inside dry neck lube, pretty much stopped the expander from pulling necks off-axis. So it's another thing you can try if you are having that problem. The Lee Collet Die remains the cat's meow for zero neck runout, though.