Robert, no, I haven't tried the SX basses yet. Unfortunately, they are only available sight unseen from Rondomusic, and I haven't run across any in my area on used shelves in guitar stores. I cannot speak for them.
Although I have never owned an instrument this far down the musical food chain (see my sig), I have checked out some Squiers, Rogues and others at the GC's and Sam Ash store in my area.
To me, Rogue's instruments don't seem completely finished. Most that I've played had frets that stick out at the edge of the fretboard. The same is sometimes true for Squiers, though not always. My son has an Affinity Series Strat, and its frets were fairly well dressed. Of course, we went through every one that the local Sam Ash had in stock. Peavey's built in the US seem to be of great quality, but those built overseas can be hit or miss. Do check them out though. I've never liked the narrow necks on Ibanez basses, but for the most part, they are a well built instrument. if you like those ultra jazz necks, you could do far worse. Yamaha builds some of the nicest "bang for the buck" instruments in the industry. That said, my old RBX774 bass, with its dual active humbuckers was no match for the Bartolini-equipped Fender "Frankenbass" I own today. I A-B'd the two and hands down, the Frankenbass won in both volume and tone catagories!
This brings me to my favorite, G&L. Leo Fender invented the electric bass guitar. No such animal existed prior to the Precision Bass. In fact, in the early days, it was referred to not as electric bass, but rather as the Fender bass. Leo then went on to create the Jazz Bass to meet the demand for a different sound. After leaving Fender (sold to CBS), Leo went on to create the Stingray Bass at Musicman. The Stingray has gone on to become another classic design. Leo left Musicman to form a partnership with his old buddy George Fullerton. The resulting company, G&L, was where Leo created the pinnacle of his designs. The L-2000 can achieve P tones, it can achieve J tones, it can achieve Stingray tones, and more. In order to reach a broader market, the Tribute line was created. Tributes are produced overseas, using USA pickups, and US designs. All Tribute instruments go through final inspection and adjustment at G&L's facility in Fullerton, CA. Talk about your bang for the buck! Anyway, the L-2000 is available in the Tribute line, and I would recommend them to anyone.
Speaking of G&L's Tributes, I just read a post by Will Ray, session player extraordinaire and member of the Hellecasters, heaping praise on the Tribute line. He owns two or three. As soon as I can bring myself to actually selling my old S-500, an L-2000 will be sitting at my house.
Now, a little about construction. Remember that there are a number of things that affect the quality of sound that an instrument puts out. While electric guitars and basses are not as dependent on wood type/quality as their acoustic cousins, what you build the body and neck of will still make an appreciable difference in the tonal quality. Some guitars in the lower price spectrum are made either from plywood or from scrap pieces of wood, glued together into a patchwork quilt. A guitar or bass made in this fashion will not sound as good as one made from a single piece or maybe two pieces of bookmatched wood. Also, the wood coming from a three hundred year old tree will generally be more stable and dense, and will produce a better tone than wood from a twenty year old tree.
Next up I would have to address pickups. Here, materials play an important role, but how the coils are wound can affect tone to a great degree also. Generally, but not always, you get what you pay for in this department. If you want clean, fat sound, be prepared to fork over some dough. Distortion can hide both lack of quality in materials and lack of playing ability, so keep that in mind!
Other hardware can also have an effect on your sound. A cheap bridge can help to make an instrument sound "tinny." Cheap pots can add dirt to your signal chain. Cheap tuners can have you out of tune in the middle of a song.
Now that I've said all of that, a friend much more knowledgable than myself once told me that people don't listen to your guitar, rather they listen to what comes out of the speakers. He went on to say that you should spend a reasonable amount on a quality instrument, but, in the end, the bulk should go towards getting a good amp/cab setup. In other words, a FirstAct guitar through a 100 watt Marshall stack will probably sound better than the best sounding Les Paul through a FirstAct amp.
If you are into roots blues, note that more of those old players were recorded using Stella's and Harmony's than were recorded playing Gibson's and Martin's. That said, the most popular of them, Robert Johnson, played a Gibson, so quality does count for something!
