This is really more of a personal preference when asking whether a full-overlay refaced cabinet will look noticeably different from a frameless cabinet that was built from scratch with minimized reveals and tighter gaps between the doors. It really depends on how closely someone is looking.
Personally, when I go to home shows and look at cabinetry, I still see plenty of full-overlay face-frame cabinets where the doors almost completely cover the face frame. We actually used to build our face-frame cabinets this way, and visually they look very similar to the newer, more streamlined frameless full-overlay cabinets we build today.
If I walked into a house and saw a full-overlay refaced cabinet with roughly 5/16″ reveals, then looked across the room at a completely separate wall of frameless cabinets with 1/8″ reveals, I probably would not notice the difference at all.
Even in high-end custom cabinetry, we regularly have to mix reveal sizes and construction methods to accommodate different situations. A good example is a refrigerator panel surrounding something like a Sub-Zero. That refrigerator panel simply cannot always work with the same 1/8″ reveals we use between standard cabinet doors because the clearance becomes too tight. We therefore have to incorporate a wider refrigerator reveal right alongside the tighter cabinet reveals. Even with those different gaps directly next to one another on the same cabinet wall, the finished installation looks perfectly acceptable.
So, if you are talking about a completely separate wall of cabinetry having slightly tighter reveals than a refaced section elsewhere in the room, I would not worry about mixing the construction methods. In my opinion, you simply are not going to notice the difference in normal use.
Replacing perfectly good cabinet boxes solely to achieve a slightly tighter reveal is difficult to justify in many situations. There is a considerable additional cost, material use, labor, and energy involved in replacing cabinetry that is otherwise perfectly functional. If the existing cabinets are in good condition and can be successfully refaced with a full-overlay design, I would personally put that money elsewhere in the project.