Also a reply to the OP @rhenager
One thing to consider is the wheel set. The spark comes with rims that have 25mm internal width. The recent trend in XC and trail bikes is for wider rims e.g. 30mm to allow bigger tires to be mounted.
I have a Trek Fuel with 24mm rims. I rode this weekend in Moab with a friend who also has a Trek Fuel, but with 30mm rims. I have 2.4” tires mounted on mine, he has 2.6”. The 2.6” tires are noticeably bigger, and probably better for the trails we were riding (I still did fine with the 2.4s). I’d like to have the option to swap between 2.4s and 2.6s with the same wheels. The 30mm rims would allow me to do that. The 24mm rims are too narrow for a 2.6” tire.
Wider tires are often suggested for people new to MTB as they are more forgiving. Wider tires also generally provide more grip, and float more on sandy sections of trail.
Emerging belief/evidence is showing that wider tires are actually faster than narrower also.
If I was buying a new XC/trail bike, the ability to run wider tires is a feature I’d look for. You’ll be able to ride fine on 2.3s and 2.4s, but it’s nice to have the option for wider tires so you can see if they work better for your riding style and conditions.
I don’t know if the Spark can run with 30mm rims and 2.6” tires - worth checking with your shop.
Sorry if this throws a wrench in your buying decision! But figured I’d flag for you to consider before dropping $4k.