As I see it:
Mouthfeel is still king whether espresso or filter. I don't like thin coffee, regardless of the exotic flavor notes.
From my limited experience, mouthfeel is coffee dependent, not temperature. Some coffees have wonderful body and mouthfeel at lighter roasts; most do not. I'm not willing to try and shoehorn a desirable feature into a coffee with expensive equipment or roast profile gymnastics that is just not there. If you want lighter espresso with a syrupy mouthfeel, buy the right coffee, not new equipment.
In general, cooler coffee tastes better to me than hot coffee. I can sip on a cup of drip for an hour after its cooled to room temperature and it just gets sweeter. I don't usually do that with espresso, but espresso is no different. Good espresso gets better as it cools. Bad espresso gets bitter and nasty, just like bad drip.
I spent last Friday afternoon in Brooklyn cupping some offerings from La Minita's microlot program. There were some relatively expensive Geisha's, some fermentation experiments (yellow, red and black honeys) and some less expensive coffees from smaller, recently reclaimed parcels that were part of the original La Minita estate that fell into disrepair.
I picked a relatively inexpensive coffee from the La Pradera farm, which is located on an Atlantic ocean facing plot across the river from Pacific facing La Minita proper. I chose this coffee because of its syrupy body. I can roast flavors in and out of coffees, but I can't roast in body without going exceedingly dark, and even then it's a false body mainly from undissolved solids.
They sent me a sample, which I roasted on my fluid bed roaster to an Agtron ground 73, and gratefully, the body was still there in spades. What a wonderful coffee!
Normally, I do not drink SO light roasted espresso; my bar coffee is Brazil/Sumatra/Ethiopia 50/35/15. But for kicks I threw a handful into my R120 this morning, and after a bit of dialing in, pulled a truly heavenly lungo from my basic lever machine into a 4oz gibraltar. It's only 2 days off the roast, so the "crema" was 80% of the shot at first, but dissipated quickly to a creamy, blondish 1/4". It was thick and rich and fruity and I sipped it for 20 minutes, a tiny bit at a time. It did not pick up any astringency and the last sip was the sweetest. I can't wait to see what this coffee will be with 3 more days rest, but it might not last that long.
So my tip...the right coffee trumps the right equipment.