It should be obvious within about 3 months or so

While I encourage waiting 6 months to see final results, it is possible to get an 'idea' of whether one is necessary at 3 months.  That doesn't mean that you should, but it seems possible that with only 300 cc's that you simply didn't have enough taken.

The question is not SmartLipo vs tumescent, but who is doing it.  It all comes down to skill here and if your surgeon isn't skillful enough or with good judgment, you can end up having poor results whichever method is used.  The problem is that with scarring from this it is going to be even tougher.  Sorry to give you that bad news, but it is going to be less likely to succeed now.  Good luck.