If I may jump in here?
Timely post in some respects because, (A) I have just collected my clone from the studios where a Band have been using it for their forthcoming album and (B) The Mate who built it for me was over here on a short stop over en route home to the USA.
Right, now NO disrespect to Nik or Ceriatone, they make a kit that does replicate an Express and I imagine that a great many people are more than happy with theirs which is great.
However, to
really nail the sound of an original Trainwreck Express it would be advisable to swap out a lot of the kit's parts and source better quality components. From what I understand, the Ceriatone components are mostly lower quality which keeps the price down. The problem here is simply that because the Express is such a Highly Gained Monster that these inferiour components tend to fail fairly regularly and make a very pronounced difference to the overall sound.
Seriously, I would suggest that spending some time over at
http://ampgarage.com would be very beneficial. These Guys know their stuff and are incredibly helpful when it comes to pointing one in the right direction.
The question of Power Scaling has been very successfully addressed by a chap called Dana Hall. His method has given exceptional results and he is a very helpful Guy.
The Express is loud, you are quite correct, but I tame mine with a beautiful attenuator that was again built by a Mate using the ampgarage schematics and I have no issues with it at all. The ONLY point I would make is that the results will differ depending on what speakers you are using. If Scaling/Reamping is going to be a regular thing, I would urge you to consider speakers that are not particularly efficient. I use a pair of Pre Rola Greenbacks and they handle this situation very well, where as my Celestion Golds...... Don't. They are fine for gigging levels, but not so good when attenuated down anywhere past -7db.