We'll be going with the 48" Titan for our 3800. It'd be nice to have a dual claw 72" unit for sure, but it wouldn't be wise to consume 250 kilos of the 524 it has to work with just manipulating the grapple. I will have no issue exceeding the capabilities of the machine using the 48".
With the SSQA I was able to hook up to a 66" 600lb bobcat bucket, and it was clearly too much for the machine. Keep your FEL attachments LIGHT, so you may be able to get as much capability out of the machine as possible.
As far as issues with Titan, and just about every other SSQA attachment company, you will need to shim them for a secure fit when using on the smaller Kubotas. I believe most SSQA machines do not have an issue with the attachments--I typically only hear this complaint from smaller utility tractor owners. Hell, for half the price of everything attachments products, I have no reservations of doing a 10min mod to a product. Keep in mind, it will work just fine without modification. It is however a little loose. I used the pallet forks this weekend to move several 1 ton pallets with the 3800 rather uneventfully. Granted I did need the help of 2 men assisting the loader to a good travel height. (You mind grabbing the pallet and helping the little tractor lift it??)
Titan is in West TN, and you can save money off their listed prices by picking the item up from them.