Well to be honest I am nowere near that sze yet but they look like a bit of a big jump to me but with plenty lube is would probably be done. Though like I said I do not know all that much at the moment. x
The bombshell seems like the best choice of those two just because the first bulb on it is the same circumference (according to a reviewer anyway) as the Exotic Diamond you have been using. Seems like a nice smooth transition :)
Also looks better shape wise as both your plug and dildo have been tapered at the end, the Titanmen one might be harder to take being rounded and you'll not know if you're struggling with the shape or the girth. I know rounded anal toys are something I always struggle with anyway. Need that bit of tapering!
either of the two plugs you've listed are a good step up from what you currently have , don't be afraid to go bigger , with plenty of lube and patience you'll be fine !!