What difference does it make if you make the mistake in a Viper or an FdL?
The re-buy cost would be the main difference.
A smaller ship to learn the ropes would be far less expensive when accidents happen.
OP, the FdL is the best combat ship there is and then you get used to the flight model it's the most fun ship too. It's harder to learn but so much more rewarding once you get into the groove.
This is exactly why people have advised starting off in something smaller.
Bigger ships generally have more module slots/hard points, so it’s very easy to just fill it with all the “best” gear without any knowledge of how to balance things and you end up with a ship that inexplicably overheats or has major power issues.
Starting in something smaller, whilst more restrictive will give you the opportunity to learn the basics (if your combat rank is low your targets won’t be flying anything that fancy anyway).
Then from there you can decide whether you want more guns, more utilities, more speed, etc and buy a ship accordingly.
However if you really want to stick with the FDL then I highly advise looking into the engineers that provide mods for Power Plants, Power Distribtors, Thrusters and your preferred weapons so you can manage it’s heat properly.
o7