I built one about 4 years ago. I bought the "oversize" version which sould have been tight in the slide rails. I used a 9mm slide which fit pretty easy. It was tight for about the first 500 rounds but has become a bit loose. It still shoots well and I haven't noticed the groups opening up but I haven't shot it much recently. The grip feels larger front strap to rear than my Caspian frames. It doesn't measure any larger but feel's bigger. The area where the trigger guard meets the frontstrap had a large radius which I took out for a higher hold.
For building an inexpensive mil-scec looking shooter I'd buy another. To keep cost down go with mil-spec parts or Chip McCormick stuff for fire control and safeties. If your going to add expensive stuff, safeties, barrel, adjustable sights then I recommend you buy a Kimber or Springfield.
I wish I could get one now but CA won't let us have frames anymore, buggers!
I built up a range gun on an Essex slide and frame and have had no problems with it. Gun has about 20,000 rnds through it and is my main grab and go blaster. I have other 1911s, but I use this one for most of my miscellaneous plinking and shooting. For the price, and the lifetime warranty, I think its a pretty hard value to beat.
I have an essex frame/remington rand slide 1911 parts gun and it has been great feeds anything i feed no ftf's or fte iam very please with it. I am also considering building another 1911 for shooting /ccw from essex parts they are of very good quality IMO
I have not used Essex slides, but have built a number of pistols using Essex frames. They seem to be GI spec, which means that GI parts will fit, but some clone parts might need fitting.
Be careful, though. Essex frames have always had sharp corners, but the last one I used seemed to have been made by Randall or Bill Moran or someone like that. Everything was super sharp. Apparently they don't tumble frames any more, so it is Band-Aid time if you aren't careful.
My very early Essex frame also has the sharp edges,I had considered relieving the sharp edges,never got around to it,did cut finger scallops(ala 1911A1, I have short fingers) in the frame to try and reduce that "bulky" grip sensation due to that front grip strap radius,helped reduce the sensation a lot,but still not the classic GI grip feeling.