No, actually a "greater" twist actually means faster twist, so a faster twist than 1-10" (1 twist in 10" of barrel length) would be 1-9". Being faster would be greater.
This for you as a consumer would mean that a bullet requires a twist of (let's say) 1-10 would also be stabilized by a 1-9 twist , but not a 1-11" twist.
As for your Sendero, That's a easy thing to figgure out if we knew what cartridge it was chambered for and that it was the factory barrel. Remington is very specific as to what twist it uses for specific chamberings and they are listed in the specifications for the particular rifle in question on their site. If it's a older rifle that they no longer list, any rifle with the same chambering will have the same twist. If you are still in doubt, you can check the twist yourself using a onepiece cleaning rod, a tight fitting jag, a patch tape and a ruler or measureing tape. It's quite easy.
Just take the patch on the jag installed on the cleaning rod, insert it into the muzzle of the barrel. Put in a inch and mark with a marker. Using tape, put a "flag" on the rod to help you indicate a full turn. slowly push the rod in until 1 full revolution of the flag is seen. then stop and mark the rod again. remove the rod and measure between the two marks and that is the rate of twist of your barrel.
Hope this helps,
Dan