Older drums tend NOT to have the most-even bearing edges, so seating the heads is a must. Plus, you're more than likely to not find the widest tuning range with older, rounder bearing edges, so upper-range tunings always seem to sound the best (which is a totally-subjective statement, I know!) because they keep the head seated and in contact with the edge better (which is NOT a subjective statement!) ;)
My philosophy has always been to use the right tool for the job. So, if you're looking for that ultra-low-range, super-sustaining, tympani-like clarity, then you will need to use big drums, rather than trying to tune your standard-size drums to sound really good in a lower tuning range.
Rounded bearing edges came from a time when most heads were made of calfskin. They worked very well for that because they didn't tear the skin. When plastic heads came into being, the bearing edges eventually began to change and get sharper and sharper -almost to the point that you could almost tune them to a specific pitch -like tympani- and get sustain for days.
I love calfskin heads, but they are expensive and fickle....When they are dialed-in...wow! So, for all practical purposes, I use plastic heads....Remo coated Diplomats because they are thin and will conform to the imperfect contours of vintage edges -creating a tighter seal and allowing more of the shell to blend into the overall sound. I also use Ambassadors -as do most people....but I just think the Diplomats are more like the old Ludwig Weathermaster heads.
There are no disadvantages to having resonant heads. That's the way a double-headed drum is designed. If you desire a concert tom sound, then get some concert toms. The advantage is that you have more tuning options with two heads. Or should I say...*wait for it*....TWO HEADS ARE BETTER THAN ONE! :)
What we used to do back i the day by taking off the resonant heads, was to avoid the overtones and feedback that happened when playing hard rock outdoors on a flatbed trailer for a stage! Just take the bottom head off, stuff the mic up into the drum and hit 'em hard! Only those weirdo jazz guys wanted two heads! ;) heh heh