I find it makes it easier to get a lucky streak and break through a peninsula in a close game. But you could be on to something.

I think it evens the chances of the game a bit. Take a theoretical 13 territory game with 2 players, where one has 7 territories and the other has 6 (all filled up to 8 dice), and there are no reserves. The first player can attack once every turn, filling up to 8 if he loses. Without reserves, the second player can't do that, and has to take a big risk by attacking. If he fails, he will have a 7 dice territory, if he wins, he will still have one 7 dice territory (as you need 8 dice to fill up), which you can only hope not to be connected to the first player.
In many cases the first player will be able to attack the 7 dice territory and have a relatively high chance of taking it. If the first player always has access to the 7 dice territory the chance for the second player to win would be around 15% (47.1% * 32.7% (win 8-vs-8 and not lose 8-vs-7)) even though he only has one territory less.

This basically means that in the current 8-vs-8 endgame you are dead once you drop below 7 territories. In the 16 dice version this would be much less of an issue though.

Ok, I can see it in that situation brain, but that's not a situation that I've noticed occurs very often. Mostly, you get one person clinch a bit of territory early on, then they sit there and build up whilst everyone else fights. Once they fill up their 8 stacks and start getting reserves, they're untouchable, and inevitably win. In my mind, that shouldn't happen, they should, like everyone else, face risk from losing an 8 stack.

Well, I'd say that is a problem in the strategy of the other players. Once the biggest players begin stacking the other players need to do the same quickly or they'll lose out, starting the 8-vs-8 standoff.
With a bit luck or an alliance small players can still be very competitive because of the reserves. So the reserves actually raise the chances of small players, where they'd be doomed without them.

<i>Once the biggest players begin stacking the other players need to do the same quickly or they'll lose out</i>

Which is /exactly/ what I dislike about it. The fact that one person sitting on 8 or so territories can become untouchable unless everyone else stops what they are doing and takes them down. This would make sense if they owned half the map, but 8 territories should impose some sort of upper limit on just how effective they can be. Players should be constantly having to balance defence and expansion. As it is, once you get that magic number, expansion takes a back seat for a while until your defence is so high you are untouchable.

The alternative is for them to attack with say half their territories, that brings them to twelve spread out territories. Guess what happens before their next turn...

Sorry, my last reply doesn't address if reserves are a good idea as well as it should.

So don't attack with half the territories. Build your stacks up so they're nicely defended, then make one or two surgical strikes each turn. It means you need to constantly keep expanding or you'll be left behind, but it also means you can't spread too thin, or you'll lose your territory.

That need for constant expansion though simply doesn't happen at the moment, and leads to turtling, camping or whatever else you want to call it. And personally, I find that style of play boring

Okay, but the only effect of eliminating reserves that I see in that situation is it'll make the player who is winning need to be even more lucky just to take one more territory.

Maybe. Obviously strategy is important in the situation I'm suggesting, as it defines how, how fast and where you expand, but luck is also an element. The game is based on dice rolls, it's inherently about luck, with the ability for an 8 stack of dice to lose against a 5 stack on bad rolls. Reserves just removes the luck element altogether, and even removes the strategy element once someone has them build up. There is no strategy to stop someone with nothing but 8 stacks and reserves, because they can attack each and every turn and still maintain 8 stacks.