Hey mate, welcome to the family!
Yep, the Drumit3 and 5 do not get enough love as far as I am concerned the edrum world, but I feel there is a momentum of people shouting their corner thankfully. They do offer something few other module does. The ability to load in custom multi samples.
Yeah, the Alesis Strike does and now the Yamaha DTX6 and ProX modules do. (I think these are great module btw) But with a limited storage limit on the 6 and a 256mb on the proX. For the most part, that should be enough for one kit of drums alone on the pro6, and a few more on the ProX module. I watched a Japanese video of a guy doing just this, but golly did it look long winded and time consuming. The results are great, but like I say, it was a bit of a marathon to achieve.
Thankfully the 2box kits, the Drumit app for Mac/Pc takes seconds! And with the 32 gigabyte card slot expansion for the drumit3 (already with a 4gig card space) and the built in slot for the drumit5 mk2, space limit is way less of an issue.
Alesis strike have a nice app too, but there is still 200mb limit to deal with. Again, if you're only talking about one or two custom kits or whatever, that should be fine. But if your the guy that wants more and more... 2box still stands alone in this field.
I made many custom samples from SSD5 for my 2box modules, and it really opened the potential. The kit will sound as good as the sound you want to put in it.