As you indicated, there are pros and cons to having a fuel cell.
Given your previous post, I gather that you are thinking about competing the car. So, a fuel cell is a good idea.
Pros:
- Less likely to suffer from fuel starvation while cornering
- More accurate fuel readings to determine mileage.
- Fuel remains more stable for a longer period of time and is less prone to evaporation
- Safer
- Fuel is centrally located and sloshing doesn't occur as much to affect weight transfer as fuel shifts inside a conventional tank (It can't do that with a cell)
Cons:
- Expensive
- Usually requires a high volume fuel pump to work effectively. The stock pump will NOT work
- Expensive
- Less fuel capacity
- To install, you need to make modifications to the rear trunk - It will not fit at the stock mounting points
- Fuel vapor can enter the car because of the installation needed
- Expensive
- You cannot pull up to the pump and use a conventional nozzle to fuel. Fuel cells are "sealed" systems that require a special filler nozzle to allow for fueling.
Bottom line is that a fuel cell is neither a good or bad idea. It depends on your application. If you intend to race the car, then definitely a good investment. If not, then save your money. The expense of the cell, fuel pump, special filling equipment and the installation can easily reach $1000 or more.