Horses for courses!
Tanks don't restrict your category of operation WRT bomb/rappel as mentioned.
You can carry water a long way with a tank without losing 15-20% of your water as a bucket will.
The look on the bird dog BO105 pilot when I overlook him in a 205 with a full tank in Spain was funny!
It can depend on the region - i.e. Tanks in Spain (Catalunya) worked well but not so much in France as we had to
carry a buoy wall all the time as the French leave the trees alongside watercourses.
Tanks with restrictors and a split drop are great on grass fires - drop at about 100 knots! Because you can.
Worked alongside a KA32 in Oz with a big bucket and it was not so effective as the fire line there is not always so straight.
Consequence of a great gut load of water limited to a single drop.
Amazing machine but the downwash would drop pretty big trees even with a longline.
The bucket wasn't something you just folded up and threw in the boot either - and of course the issue with underslung in an urban area.
Tanks that I used were Conair/Frontier system - about as complicated as a Jet Banger!!
About a 40 second fill time which is significant as per SAS's video although it helps if you don't stick it in the mud!
When it all turns to custard the best machine I have seen is yellow with CAT on the side!!
That plus a torch to light up behind it. It can only burn once. But I digress...............
If I was a house owner under threat of a fire the last thing I would do before leaving is ring burn the joint! But that's possibly "illegal".
Did about 1200 hours with buckets and about 750 with tanks and then moved on....................