In my experience with Lincoln, their smaller welders are good if you're laying a good long bead, but they **** if you're doing a bunch of spot welds, ie; stitch welds. They don't seems to be set up well for it as the trigger and drive motor lags too much and they have alot of problems with burnack. Now the larger machines do well and don't have these problems. In my shop, I have several welders. 1-Millermatic 130XP, 1-Millermatic 250x, 1-Miller Diversion 165 and an Esab Multi-master 260(Jesse James Model). Now, I know your gonna say, why so many!!!! Well, the 130 and the Diversion are on one cart that I can roll anywhere and mostly for thinner metals, and aluminum. And the 250x and the Esab are for the thicker stuff.....framework etc. My favorite of them all for the mig process is the Esab. Simply put, it's perfect!!! The burnback control is your friend, and even when you get in a hurry, won't let you weld the tip up to the contact. And my favorite for the Tig is the Diversion. I added the foot control to it, and while building alot of custom aluminum intakes, the arc is so controlable at lower amps than the Esab. The Esab will not do AC(aluminum). But is very handy when i'm welding up custom SS exhausts and lakes pipes.
Now this all said.......it all comes down to your own welding ability. I will tell even the dude that has been welding for 30 years, you can never have enough practice. Every project is different. Different parts, layout area, positioning and so on........ to those who know me personally, know that I have a prosthetic hook!!! on my left arm. So I have to re-position alot to get where I need to be to weld what I feel is acceptable....and I'm very picky. I don't get in to big of a hurry when tig'ing, but I do while mig'ing, but the control is all in my right hand then so I can move along well....
e-tek, ask yourself this, is that MigPak 180 gonna do all you'll ever want to do? If so, buy it. But if not, use what you got while you save, and look for a bigger more suitable machine that is new or used. For an extra 5-600 $$, you can get an excellent used machine that is bigger and able to do more. Also look at the Spoolgun factor. Is the MigPak 180 able to take spoolgun? Some smaller machines aren't, and if you ever think you may want one, then go ahead now and buy the appropriate sized machine.
Before I get flamed......this is only my opinion, though it's mine from experience.