Yeah, no machine was clearly better than the other.
In terms of build, there are a few areas where the machines differ. The expobars have awesome, deep drip trays, but the top is the standard sheet of metal with holes through it that most machines have, so it collects a bit of mess on top of it. The giotto has a shallow drip tray (probably needs emptying after four or five shots) but the wire screen that fits on top of it doesnt allow espresso muck to pool up on top of it. The expobar has a reservoir that cant be filled in situ without a funnel. The ECM reservoir (updated on this years giottos) has nifty little handles on it so that it can be lifted out easily, or you can just fill it in situ
I thought that the giotto was awesome in the steaming department (600mL jug), but I didnt really try the brewtus. The giotto had an experimental tip on it that was not as good as the stock tip. Kinda reminded me of steaming on a La Marzocco Linea. The expobar didnt thrill me, but thats just a matter of tweaking - you could take the shell off and dial the pressurestat up* pretty easily. Hell, you could also get the apparently awesome steam tip from Pedro at coffeeparts or just buy the giotto steam arm and retrofit it to get identical, if not better, steaming out of the expobar. So both should be fine for milk drinks.
Obviously the expobars temperature tweakability was easy and pretty cool, but I though that you could do a fair bit with the giotto as well. For example, you can flush and brew immediately or flush and wait 30 or 40 seconds to get a hotter first part of the shot. Getting at the pressurestat to adjust that is fairly easy, too; you just need to take four screws off the top; you could probably even tweak the pstat* through the cup warmer holes. Anyhoo, we didnt bring screwdrivers to tweak the giotto, so I guess that that bit goes largely un-tested. What is true is this: if you dont have a really, really consistent technique, temperature control will be utterly lost on you.
I brought along a rather amusing coffee to see how much we could tweak the giotto: a light-roasted and stale Kimmel. Tweaking the grind was far, far more important than anything else. We flushed the machine until the steaming stopped, then waited about 45 seconds until brewing to allow the water at the start of the shot to heat up and, combined with a very short pour, Chris was able to mute a surprising amount of the acidity. There is no doubt, though, that tweaking the grind was far, far more important than tweaking the flush. And, to prove a point, no matter how good your machine, grinder and technique are, nothing rescues stale coffee!
With regards to all of this tweakery that Im constantly talking about, I dont think that this is something to even think about if its your first machine. The beauty of buying from someone like Chris is that you will not be shipped a machine that has not been bench-tested and tweaked to the point where all of the variables are in a useable range. This means that you can safely just focus on developing technique for the first six months or so ... hopefully just with one blend thats roasted by a consistent commercial roaster for you, so as to eliminate that variable. Getting a consistent dose, for example, is actually very difficult.
Overall, I find it difficult to imagine being disappointed with either machine. Each has its own idiosyncracies and can be expected to out-perform the operator. If I had to choose one, Id probably ... uhh ... go for ... the giotto. I guess. Just because the idea of playing with a heat exchanger machine has some novelty for me because Im using either single boiler or multiple boiler machines these days. But really what Id ideally want to do is to swap machines around every few months ;P Or buy both. One for upstairs and one for downstairs. In terms of grinders, on the other hand, Chris and I both agreed on our mutual hatred of stepped adjustment!
A huge thankyou to Chris for giving us the opportunity to turn up late ( :-[)... err ... I mean, to play with your toys!
*I know that I talk about dialling the pstat around a lot, but remember that these things are fragile - you can wreck them if you dont tweak carefully. If you smash them, theyre something like $50 or $100 to replace ... not that hard of a job. And dont expect vendors to be sympathetic. In fact, if you take the top off your machine, dont expect any vendor to be sympathetic if anything goes wrong!