Hm, I would have expected it to be more like 6 and 7. In any case, I'm mainly doing the route for the sake of the storyline. This is one of the reasons I prefer Fire Emblem to Tactics - I feel as though I get significant plot development on a regular basis. Admittedly this is just Advance, but I felt similar even in what I played of the original.
Tactics (the original) was a bit slow in Chapter 1, but I think you would be pretty satisfied later on. Tactics Advance just didn't really have enough plot...
Eirika does have a pretty neat story route. It has a smoother transition than Ephraim's, probably because you have Eirika from the beginning and Ephraim doesn't come in until later.
In Fire Emblem, there have been at least two missions where I could only recruit a unit or save a village by trying for them from the very first round. No amount of reacting to the situation could have accomplished it, so I had to restart and have that in mind from the very beginning. That's a bit frustrating.
This is another thing I actually think 8 toned down from 6 or 7. Their are some pretty tricky maps that require near perfect timing if you want to get everything.
Those indoor maps where you have to work fast to get all of the treasure from the thieves tend require really good timing too.
One of the chapters I recently finished in Fire Emblem VI is a combo desert + fog of war map. Thus, anything that's not a Mage/Druid/Priest or flying unit gets a movement penalty, and horseback units are nearly useless. There are 3 Mamkutes/transforming dragons that are really difficult to kill. You are attacked by 2 Berserkers and 2 dozen Fighters from behind you halfway through the chapter, and you have to complete the chapter within 25 turns if you want to go to an optional chapter.
This map could be nasty, particularly since it really forces you to use a number of generally fragile units.