I have got the 2.5 classic T-Maxx that I have put a 3.3 motor into. This is a great truck to own, light, tons of parts available, at least at my lhs, and yes it is very easy to work on But, As mentioned above, you will have to put some money into beefing it up to savage strength for sure. I have got Golden Horizon bulkheads and chassis braces (in stock form to answer your question are prone to breakage), as well as RPM skid plates all the way down the middle of the chassis and it cost me around $150. The T-Maxx is also really fast due to its light weight...until you start to add alot of heavier aftermarket parts to it (but that goes for any rig really).
I have also heard from others that the 3.3 is a very easy engine to keep tuned, and for me that has been very true. I basically just adjust the hsn lean or rich depending on temp outside and go.
Now my T-Maxx is pretty darn tough, they are stock anyways, but Traxxas stock plastic just doesn't seem to be as strong and rigid as the HPI stock plastic.
How much are they asking for the Tmaxx at your lhs. T-Maxxes are generally cheaper than the savage.