I owned the 15G2s for 8 years, they have been great speakers and I'll be keeping them as a back up. I had been looking for a replacement because as good as the G2s are, the weight was getting me down. I know they're powerful and not as heavy as many speakers, but they still caused me issues going up stairs and mounting them on stands being a person with a dodgy back! My duo partner (guitarist) called them "The Brutes" because we both hated lugging them around. I know in the grand scheme of things they are actually not that bad considering how much power they have, but the newer class D amplifiers and technology became more and more alluring!
When I was first looking for new speakers the XTs had not been released, and I was put off the original 515s because of the reports on forums that they weren't as powerful as the G2s and needed a high signal from the mixer to drive them properly. I have always liked RCF gear, so I ordered a single RCF422a from Absolute Music online (I live in Maidstone, and they're based in Bournmouth so I couldn't go in for a demo). The RCF had a beautiful sound, very compact and very hi-fi sounding for a loudspeaker. The weight was better but still 18kg. One thing I noticed was, there wasn't as much power as my G2s, it had less bass (being a 12" speaker I guess?) and also the top end didn't cut through as much. But overall playing CDs through it was very good, it just didnt sound that great when I was singing through it because I had to turn up the vocal mic so much to cut through it would feedback easily, and I'd need to turn the backing tracks down as well.
The RCF had a very balanced hi-fi sound with lots of detail, and if I were a DJ I imagine I'd prefer it. However, since i play saxophone and sing with a soft voice it is important to me that the vocals cut through with ease. This has always been something that the G2s have done well. Although the tweeters on the G2s are a tad harsh, they are good for making sure the vocals are heard over the rest of the band/music playing. So I sent the RCF speaker back to the shop within the 7 days under distance selling regs. Have to say, Absolute Music were brilliant, they just took it back with no questions asked. I waited a few months as I was unsure what to do and decided to stick with the G2s for a while.
When I heard that JBL had addressed the issues that concerned me and released a new model (515XT) I decided to take another gamble and buy one from Absolute, knowing that if I hated it I could send it back like the last one. When it arrived I put a G2 and 515XT side by side with my main set up connected to compare. The 515XT sounded more hi-fi with a nicer mid range, plus it had more detail. The horn wasn't as harsh as the G2 at higher volumes and generally sounded more rounded and complete. The 515XT sounded notably better to my ears with all kinds of music, and my vocals and sax still cut through the mix nicely. I also couldnt detect any distortion at high levels. The weight is wonderful, they're a pleasure to use and just as powerful too! So I ordered a second speaker to complete my set up. I have been gigging with them each weekend since January, and I have had lots of complimentary comments about them, the bottom end is nice and they seem to sound good everywhere we play. I genuinely couldn't be happier with them, and I'd buy them again in a heartbeat.
I can't comment on the reliability but I feel happy knowing that I have a 3 year guarantee with Absolute (if you sign up for their newsletter you become a VIP member and automatically qualify for that). Also, the heatsinks on the back are barely warm after a long gig, so I feel comfortable that everything is working nicely.
Finally I should mention, I did buy some padded bags for them, but they weren't for me - way too big and the huge handles were cumbersome. I ended up getting some of these which I much prefer: http://www.soundslive.co.uk/product~...X~ID~12564.asp
I actually bought a pair of the covers from whybuynew at £59 but I don't think they have stock now. They have a velcro bit on the front which rolls them up so you can use the speaker outside with the cover on, but I think you're not supposed to use them on powered JBLs, as it may not allow the heatsink to work properly - there's a label on it saying something along those lines. But for transporting to gigs these were a better option for me (as I remove the covers anyway).