I own both an RT 820 (older steel covers vs, RT 82-newer fiberglass body) and a BMP 8500. Both purchased used (RT had =/-400 hrs; BMP had about 180). I've had the Wacker RT for about 8-9 years and the Bomag for about 1. I bought the RT from a dealer and paid about $17k for it and the Bomag was purchased from United Rental for $8k (IIRC). I like CM's pricing much better...maybe I should look back east next time i'm in the market!
Both are handy machines and like CM said we use ours much more than I do my 66" single drum roller. I have also had a few electrical gremlins in both of my Wacker RT 820s (I've owned two-one prior to my current). I hate electrical gremlins and that's why I didn't by Whacker this time (along with high parts pricing/poor availability and support in my area). It's also why I traded in the first RT. It had either a controller issue or an ECM issue...Both are very expensive things to replace. It turned out to be a controller issue (dealer replaced and re-sold). Bomag has a PIA safety feature called a proximity sensor. If the control box gets too close to the machine everything shuts down. Machine will also not start if too close. Operators find this very annoying even if it is a safety feature. The Bomag is a
LOT quieter than the Wacker. This is probably less so when comparing to a newer RT 82 instead of the older RT 820. I think the Bomag hits harder (it is definitely a heavier unit) and works better for dirt compaction. I prefer the Whacker for gravel compaction/slab prep. I'm not sure if it's the frequency or if it's the design of the roller shells (RT is not as aggressive as the BMP). I also think that the RT 820 hits harder than the RT 82 and I prefer the prior to the latter. Biggest issue with the 820 now is that Wacker is not making a lot of the parts anymore. The Bomag doesn't finish well when in gravel. We often will finish with a plate compactor anyway but we find that we
MUST do so when using the Bomag on gravel. I have had a few problems with the Lambardini engine (in the Wacker). Mostly oil and fuel leaks. If I recall correctly the Wacker grenaded the bottom end (eccentrics) within 40 hrs of purchase. It's been fine since repaired (Dealer and Wacker both stepped up to make it much less expensive for me). Regardless, change oils religiously. On that note I think that the Bomag is a little easier to service. Lambardini engine can be difficult to get parts for. The manual often shows several part munbers for the same part and your S/N is not helpful in determining which part is the right one for your unit. This can often lead to several processes of going to the dealer, ordering, waiting , and trying part out. That's frustrating! I would not expect this from the Kubota engine but don't yet have any direct experience with this engine to draw from. As a general rule I like Kubota engines and have seen many with a lot of trouble free hours. My current Bobcat 435 ZHS mini-ex (which hasn't exactly been a trouble free machine) has over 5,500 trouble free hours on the Kubota engine so far. Over-all I think both are good machines and each have their own strengths and weaknesses.
I have a great contact in Wake Forest NC that repairs remotes on both brands. Sent the Wackers remote to them, quick turn around and fair pricing.
I have had to send my Wacker controller in for repairs as well (steering lever failure). I think it went to the same place...Carolina Electrics? I wasn't super pleased with the repair. The lever now works but one must only push forward part way. If pushed to the stop the machine stops moving. This is a small annoyance and has not gotten any worse for several years (As I feared it would). I would use that shop again. If you are using a different shop I would like to know which as it is very difficult to locate repairs for these units and having options (in case one goes out of business, etc) is always a good idea.
As a dealer mechanic for a Bomag dealership the BMP8500 has been a very good machine. The only areas that have been giving us repeated problems is the "phone cord" that connects the remote to the machine like CM1995 said. Also stay on top of the rubber isolators. We have seen that when they get worn the body of the roller contacts the fittings on the wheels (usually at higher hours) and if allowed to go long enough will break the fittings off (sometimes ruining the threads on the wheel's center section). So at the first sign of contact replace the isolators. Good luck with your choice.
Can you please elaborate on where, exactly, I should be watching for this contact?