Verso and Every Stage FX are identical seats except that the Verso is not approved to be used in forward facing mode with harness. You can only use it forward facing as a booster. To be honest you probably do not want to use the Every Stage FFwH either, because it gets poor crash test results when used in this way. The Stages has not been independently tested so I don't know if it has the same problem when forward facing with harness.
The Stages is meant to be a bit more universal and easier to fit than the Every Stage. This might be important if you are moving it between cars.
The point about them going up to different ages only refers to the high backed booster stage. The Stages fits a child of up to roughly 125cm whereas the Every Stage/Verso will probably fit up to about 140cm - it's a standard sized booster.
The Stages/Every Stage/Verso are good in theory for tall-but-slim children, because their harness is able to be adjusted right up to the top of the headrest even in booster mode, but has a weight limit of 18kg.
I am a bit wary of these seats if I am honest at the top end. Plenty of people use them and find them fine and I have seen several photos on social media of awful crashes where the Joie seat survives intact, which is really a credit to them, and it's very useful that they are able to be used to a higher height, my concern is simply that this is the only company whose seats allow this - and why? Every other company which makes a seat that covers both Group 1 and also converts to a booster seat has some kind of limit where the Group 1 harness can not be raised any further, usually around the size of a 105cm tall child. Some (tall but slim) children are 110-115cm tall by the time they reach 18kg, yet most Group 1 seats are designed for children up to about 105cm tall. (Group 2/25kg seats are designed for children up to 125cm tall, so we're talking halfway to this limit.)
One reason might be - because 75% of children at 105cm will still be under 18kg, it prevents the harness accidentally being used by parents beyond the weight limit - and I have heard of this happening with these Joie seats. It's quite a common error and it could be quite dangerous, as the harness could fail. If this is the only reason then there is no problem from a safety perspective, simply that you must be aware of it and not use it for too long with the harness.
But the other reason might be that crash tests are done with standard sized crash test dummies. There is no crash test dummy which is 16kg and 110cm tall, which may well be the size of a real child rear (or forward) facing in a Joie harnessed seat. That means you don't really know how that seat is going to perform with that weight distribution (head height) in an accident, because the dummy which is taller than 105cm is over 18kg and therefore would not be tested in that seat configuration. Several Britax forward facing seats have been changed over the years from a 25kg harness to an 18kg only harness, and the only seats available today which are 25kg with harness forward facing have top tether (which none of these three Joie seats do) - that suggests to me that without top tether, a child over 105cm forward facing in a harnessed seat quite possibly experiences too much forward head movement which is the biggest cause of injury and death in a forward facing seat. In rear facing this probably isn't a concern because the car seat is supported by the diagonal part of the seatbelt, but again if you look at car seats designed for taller children, none of them fit like an infant carrier with the seatbelt going around the back. They all use tethers or bracing to support the backrest of the car seat. So I would be concerned that for a child over about 105cm, even if under 18kg, it's possible that too much of their body weight might be above the point of the seatbelt, causing the seat to move too far forward and potentially collide with the seat in front. I don't know that this would happen, and of course it might not. I am just thinking that it could be a possibility, and there must be a reason that other car seats don't allow the seat to be extended higher than the norm.
If you do want to use the seat significantly past 105cm height, I would look again at the 25kg ERFs to be honest, even if just as an additional option, simply because these seats are designed for children over 105cm and 18kg. The tethers are not as fiddly as they sound - certainly much less annoying than posting your child over/under a seatbelt every time you fit them in the seat. Most Group 1 seats are annoying to move from car to car anyway because they are heavy. If there are two or more cars you use regularly, you can buy a set of tethers for each and then it's literally a case of clipping and unclipping. It would probably be more of a problem if you don't have your own car and you need a seat for hire cars/taxis/lifts. The tethers don't get in the way when not in use and they don't cause any damage to the car either. I'd have a look on youtube as there are a few demo videos which show how quick they are to do once installed for the first time.
There are a couple of 25kg ERFs which don't use a support leg - Britax Two Way Elite and Diono Radian 5 off the top of my head, I think? Not sure if others have/need one.
The other one I'd look at is the Concord Reverso. This one is good for children who are heavier, because it has a weight limit of 23kg, however as an i-size seat, it has a height limit of 105cm which means effectively it is the same size as (most) 18kg limit seats. There seems to be a bit of a disagreement at the moment among manufacturers and experts (neither group has a "side", there is mixed feedback from all) about whether you can safely use it after 105cm if your child fits the usual criteria - head inside seat shell etc. If you can, then it would definitely be an interesting/useful choice to look at.