I don't believe the DB115 has a tweeter in it.
The only IRs I've tried blending are the Hartke Redwirez. I use a Stomp for my IRs, so I can load two... I posted some audio samples in
post #94 of this thread of the Hartke IR. It's got a dry reference sample, a sample with just one of the 10" woofer IRs, and then a blended sample with IRs for both a 10" and 5" woofer. I don't remember which specific IR models I used, though. I never tried blending in the port IR... Might be worth going back and trying it out, but I can't currently load all three at once.
I like the blended Hartke sample quite a bit, because it does remind me of the Hartke Pro 4200 I used to have. But that also takes an extra block in the Stomp's signal chain, and I do tend to prefer the sound of other single IRs more. (Currently the Redwirez DB115, Dr. B's Ampeg PF115, and the Shift Line Heritage B15 is pretty awesome with my P bass with flats. But also finally got back to tinkering with my 8x10 models, and dialed a couple in a bit more last night).
5sg.