First of all, you should compare apples to apples. The Remington is a heavy barrel, 7.5 lb rifle. The T3 Lite is only 6 lbs, 3 oz and has a regular barrel.
You should compare the Remington to the T3 Varmint instead which is 8lbs and has the heavy barrel.
I can't speak for the Remington, but I own the Varmint and I can't say enough good things about it, but it's not really a gun that is at it's best shooting offhand. It's for shooting off a rest or bipod, pure and simple. If you are willing to find something to rest it on though, the accuracy is absolutely outstanding and worth the trouble. I can easily shoot less than one inch all day long with factory ammo at 100 yards with mine.
I don't think the T3 Lite will be quite as accurate, but it is much lighter and I'm sure will probably do 1 to 1.5" at 100 yards quite easily with factory ammo.
I don't have anything against Remingtons, but I prefer the Tikkas hands down.
The detachable mag is very much the way to go. You don't end up with your rounds falling all over if you want to quickly unload, and in spite of what some people will try and tell you, the mag isn't easily dropped or broken. I've had no issue with mine and find it funny to watch my friend that has a Savage Predator pick up all his dropped cartridges when he "unloads" his rifle.
Hands down, go with the Tikka.