the path you choose is up to you, as SCing IS possible, but it is not the best option for power- best option is to buy a SSEi or a SC SLE.
Actually it IS debateably the best option for power. Turbo being the other. With the 9.4:1 compresion in the L36 the gains are awesome.
With a base top swap costing ~$1800 installed and a base turbo ~$3000 installed, you decide.
As far as "creature" comforts in the Bonne levels I dont know. GPGT guys top swap all the time, and they have the same comforts as a GTP owner, and the TS'ed L36 will walk all over the L67.
As far as dependability in the trans, assuming you have a healthy trans to begin with, you will see no problems. Unless you drive like a fool. The only issue with the non-HD trans is the diff being smaller.
As for the 4t60 guys, you will see problems. Granted some are doing quite well, but to me its just a time bomb.