Wow, I can't believe I missed this post.
I'm of a different mindset when it comes to BBQ'ing and smoking. I have an offset smoker/grill very similar to Majors. My friend has one identical to it. You can smoke on those, but you have to very careful. The side nearest the firebox will run hotter than the furthest end. You have to account for this. The other option is to modify it by placing a steel baffle in front of the firebox. I completely removed the firebox from mine.
Personally, I don't believe in combination units. I have never found a grill of any kind that can smoke as well as a unit designed specifically for smoking. Likewise, I have never found a smoker that can grill as well as my Webber.
Having said that, I'm sure there are some units that can do both. I don't know which Treager Collector has, but I'm sure it's probably pretty good at both. Treagers are the Cadillac's of the grilling world. I don't own one, but would love to!
If budget cooking is what you are looking for, there are two things you can get to have the best of both worlds without breaking the bank.
First, for grilling, get a Webber Kettle. The One Touch Gold (OTG) and One Touch Silver (OTS) are both excellent units. The OTS will run you about $130, the OTG a bit more. There is also a One Touch Platinum. I priced one at the local hardware store...$399! I'll pass.
For smoking, you can't beat the Upright Drum Smoker (aka the Ugly Drum Smoker...aka, the UDS) The UDS is simply a 55 gallon steel drum that has been converted into a smoker. It will hold temps extremely well and is very stable. You can build one for about $100. It doesn't take a lot of skill, but a working knowledge of an electric drill would be handy.
Here are a few pics of my UDS during construction. The trick is to find the proper drum. There are several theories on this. You first must decide which type of lid you want before you get your drum. The lid from a webber kettle will fit most drums, but not all. If you have a spare lid, or can get one, take it with you when you get your drum. If that is the lid type you want, you will want to buy a closed top drum and you will have to cut the top out. The only advantage this style has is that it gives some extra height in the smoker. Personally, I have never needed the extra height.
The other option is getting an open top drum. This style uses the existing, removeable lid from the drum. This is what I have. It's less work, and the lid seals tightly.
Another thing a lot of people debate is knowing what was in the drum previously. The drum I bought had an unknown substance in it. It looked like old goopy white paint. The drum also had what is known as the dreaded liner. That's why I didn't care what was in the drum. That liner is impervious to everything. If you remove the liner down to bare metal, whatever was in the drum is also gone. I don't buy into the food grade drum only argument for that reason. Removing the liner is the hardest part of the entire project. There are no chemicals that will remove it. It must be removed by hand with a lot of grinding and sanding. It won't even completely burn out. That thing is tough!!!
I have more pics of the building process somewhere if anyone is interested. I can also provide instructions for building one.
Here is the firebox I built. The ash pan is an old 16 pizza pan. The coal grate is the coal grate from a webber kettle grill. You can buy replacement grates, both coal and grilling, for the webber kettles. The coal box is simply expanded metal bent into a circle and bolted together:
This is the interior of the drum after I removed the liner and installed the parts. Heh, it didn't stay shiny for long

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And here is the finished drum smoker. The total cost was about $100 which includes the cost of the drum and all brand new grates and hardware:
Here are a few notes on versatility, and why I have so many grills.
I baked this bread in the Webber OTS. I like the OTS for baking because it gets hotter than the smokers. That's not to say I can't get the smokers to 325 or higher, but it takes much longer. The OTS is much more efficient.
I use my large offset for grilling very large cuts or large quantities. It is also the only grill fitted for the rottisserie:
Here are the two smokers in operation at the same time. The large hose you see going to the bottom of the UDS is from a homemade tempreature controller I built. You do not have to do that! The 3/4" ball valve works great. I built the temp controller for very long cooks like slow brisket so I could get some sleep:
And just for Baymule, bet you can guess what this is Bay
So, after all of that, I would recommend two things. First, decide what you want to cook, but beware, it's addictive. Second, decide how many people you will eventually be feeding. You can't really go wrong with an OTS and UDS combo. Neither will do everything well, but having both will do nearly everything perfectly.
Just remember, cooking with these does have a learning curve. It takes a time and practice to get used to how your gear cooks.