As Scott said , the blade clamping system is key , stay away from anything that requires tools to change the blade. Pinless blades are preferable to pinned blades, as pinned blades require a larger entry hole and negate any detail cutting. Another thing to look for is " bottom feed " or " top feed " or both. This relates to the direction in which you feed the blade through the entry hole. With bottom feed, the blade is released from the upper clamp, the piece is lifted and the blade is threaded through from the bottom . I'm a " bottom feeder " ( ask my ex-wife :lol: ) but it is all in what you get used to.
As for the Dewalt 788, I have one of these machines and it is by far the most bang for the buck in my opinion. The 788 is sub-divided into 2 types. Type 1 and type 2 . This info can be found on the data plate on the motor housing that protrudes to the right . Dewalt moved their production overseas some time ago and began labeling them type 2. Type 1's are very hard to find ( almost always found used ) and definitely the superior machines. Dewalt had some production issues for awhile that resulted in less-than-flat tables and problems with the spacing of the blade clamps. The clamps were slightly too far apart resulting in issues with blades not staying securely clamped . This may be the issue you have read about with clamping. These problems have been supposedly fixed but there are still a lot of machines out there with the defects. The 788 is an awesome machine but I would hesitate to buy one that I could not "test drive" first .
I cannot comment on the Delta but know many scrollers who use them and are happy .
The initial question is "what kind of scrolling do you want to do ? " Throat depth varies from as little 14" to as large as 26" depending on the machine. Does the table tilt for bevel cuts? Is the upper arm fixed or will it lift ? This determines top feeding or bottom feeding ( or both )
If you find something specific, holler out. There are some awesome scroller on this site and I'm sure ( like me ) they have all done the same research and can provide specifics.
sorry for the long-winded answer, but it is so rare that something comes up on this forum that I actually know something about :rolf: