So Rick, Have you tried rings vs. long dovetail?
I just picked up one of the costco scopes for $100 off of craigs list. For that price it just can't be beat. Everything is metal except for the focuser wheels (maybe the lens cell is plastic too). I haven't really put it through stringent tests but it did fine on Mars with 7mm zoom. The tripod/mount seems a bit wiggly. A breeze made it only possible to view Mars after the scope settled down, and I was using it with the legs all the way down.
I have not tried the included eyepieces. I think the dovetail is a bit short, and the scope may not be balanced. Although I did use a better diagonal and svbony 7-21 zoom, which weighs a bit more than the included diagonal and eyepiece
This is not an AT ED on an sterllarvue M2c, but look at the price!!! A functional telescope that a single parent family can afford. At our star parties, I have moms with daughters interested in astronomy, and when they ask what the price for a starting telescope is and I say $800 (dob + accessories) i see a look of astonishment on their face.
Yes I have! Obviously both work fine, but I prefer the long dovetail attached directly to the OTA. It give me lots of adjustment for balance, plus the scope fits in the snug carry bag I bought for it (it will not fit with the rings on it). However, I have a bolt at the end and middle of the dovetail that thread into the scope, but I will likely drill and tap a 3rd hole for the other end of the dovetail so it is firmly affixed to the OTA.
I don't use it on the stock Omni mount anymore (that's now used with my 70mm refractor) and instead I only use it on either my AZ4 mount on my EQ5 mount (if I want tracking). I also upgraded the diagonal and I gave away the eyepieces that came with it - I have much better glass in my case!
For the price, I think this scope is one of the best values out there. I mean come on! A 4" refractor for peanuts. I paid $200 for mine (including the tripod), and all I did was put a better diagonal on it (which I already had - an Orion 1.25" mirror) and some aluminium focus wheels (again, Orion) which again, I already had. It handles power pretty well - I can put this rascal up to 165x and I get nice Airy disks on stars. The CA is obvious, but I have an Svbony 231 filter that helps. If I'm looking at something really bright (Venus, Moon) then I have a 66mm aperture mask to make the scope an f/10 system and that tidies things up tremendously.
A really great scope! I agree it's no AT ED, but for the price... if you want a 4" refractor on the cheap... there's not much out there that can touch it. 
