IMO yes, but I like lots of options. Someone once commented my keeping of an FL80 and a Flex head Matco88 on my cart was redundant. I disagree, even if both were of the same brand.
Obviously the flex offers more features, and with something like a Matco 88 tooth you're not adding much bulk. So what downside does the flex offer? For one you're going to wear out the flex mechanism over time. The pivot point is inherently weaker than a solid piece of steel. When your ratchet is used in the unlocked position it will become floppier over time as the U shaped area wears. BTDT, even with a warranty I just don't want to do so if I can help it. I've done this to a couple 3/8 ratchets as you can really put some power through a longer 3/8 ratchet which is an inherently small handle size.
The other issue is wobble, when putting maximum force on the ratchet. The mechanism to lock the head always has a little play, and at really high torque loads you can start wiggling the ratchet as you increase the force which increases your likelihood of slipping off the fastener or hurting yourself. Sort of like getting death-wobble on a long flex head that doesn't lock where you start swinging back and forth and need to abandon to pull/push attempt. So much so that I don't like 1/2 drive flex ratchets without locking mechanisms because that can get dangerous fast.
That's mostly an issue at really high torque loads, but I specifically don't like flex head anything for exhaust work as a result It's not uncommon with a fastener glowing red I still apply enough force on a ~11" 3/8 ratchet to cause it to auto-reverse and pop off the fastener when it finally cracks free. SK, gear wrench, snap on, matco, basically anything can be coaxed to react that way at high torque loads and sudden changes in resistance.
With all of that said, one could absolutely use just a good quality locking flex as their main ratchet. I just like optimal solutions when possible.