I have both the 520EXC and the DRZ400e, and I love them both. However, they are virtually night and day. The KTM is the ultimate machine, without doubt, but it's truly an all-out type of bike. I've seen lots of posts about the cost "plus all the add ons," but there's virtually nothing you have to do other than some tuning, bark busters if you're so inclined, etc. So the cost is justified, and it's bullet-proof if you're even reasonable about maintenance. I use it primarily in desert riding and truly nasty rocks out at the family place in southern New Mexico. I've never ridden a better bike, anywhere, anytime. That said, it's more money, more attention to detail, more cost on parts, and it really is not the best trail/plonking bike because of the tremendous power-to-weight ratio.
The DRZ, on the other hand, is THE ideal trail bike (except for maybe KTM 200EXC, but I don't two-smoke, and I don't do the louder-than-a-Kiss-concert thing, either). It is virtually maintenance and trouble-free, and it handles great. Smokes the XRs that are close in weight, and doesn't handle like a rhino compared to the XRs that are faster. I mostly ride it here in Georgia, but have ridden my Dad's (67 year old former fighter pilot and enduro crazy) in the west. Does great virtually anywhere. Weighs a little more, but so what? The weight is low, when trail riding I'm not doing freestyle MX, and the overall demeanor of the bike is great. I can ride with my beginner son and not leave him frustrated (the KTM would be too much), but there are few who are so much better that I can't keep up with them on their bikes (whatever they are) when I'm by myself... and if I can't keep up with them, then they're probably so good that they could smoke me on a 125EXC! Finally, if you're even thinking of dual-sporting, the DRZ is perfect. However, if you're one of those folks who wants to do a big hop-up (beyond a couple of great ideas for freeing up power for less than 10 bucks), then you should go right for the 520EXC.
The only other e-start option is Husaberg, but check out any Husaberg board and you'll see what a hassle it is to keep those things up. Appears even the new ones are still finicky and rough on bearings. Have heard that they are working hard on this and the bikes are absolute banshees, but they are truly exotics for those with lots of talent (in the garage as well as on the track) and spare time.
Hope this helps. I think you'll be happy with either bike, or even the KTM 400EXC. Just keep the oil coming!