You're going to get quite a variety of answers on this one...
The TA05 is an excellent car... but it's not in the same league when it comes to being a "true race car" when compared to the 415. Yes - the TA05 can win some club races, however the comparison is like comparing a Porsche Boxter S to a Porsche GT3. Yes - both are still Porsche's and although the Boxter is a great car for doing some track days, it is in no way a performance based machine like the GT3.
To put it bluntly, if you are looking for a higher perfomance car the 415 is a better bet - however, expect to break more stuff when you hit the boards and be more sensitive to not being set-up perfectly. The TA05 is a great multi-purpose car that is excellent for the new-to-intermediate racer, expecially if you are looking at racing at outdoor events. The car is a little more forgiving in crashes and with the stock suspension, more durable.
Hope this helps. Eitherway, welcome to the hobby.