I have owned 3 OD1s before, and all of them are of different versions. To my knowledge, there are a few versions of the OD1. On the Bossarea website, they label the versions as OD1A, OD1B ... and so on, with the earliest version being the OD1A and the last being the OD1E. There are several ways to identify each version, but the best way in my opinion is by identifying the marking of the PCB and the op-amp it is using. Generally, the OD1As and OD1Bs had the 14-pin op-amp on them, while the later versions had the 8-pin op amp and are typically a 4558D. As different op-amps are used (the number of pins are different), there are some very very minor changes to the circuitry. Most argue that these small changes have little changes to the tone of the pedal from version to version, but my experience tells me otherwise. I find the OD1A and OD1B with the 14-pin op-amp much warmer and thicker than the other versions. I read before that this is due to the 14-pin op-amp which introduces more noise into the signal, that fortunately (or unfortunately) thickens the tone. Some also argue that the momentarily LED also makes a different. Whatever the case, I do find the 14-pin op-amp OD1s more appealing and they are a keeper. I am glad that I got one of the earlier ones cheap, but I observe that these earlier ones can go for 400sgd easily on ebay.
Circuit-wise, the later versions of OD1 with the 8-pin op-amps have very very very very very similar circuits to the SD1. So similar that if you play "spot the difference", it is actually very hard to spot the difference. In fact, you can modify the SD1 into a later version OD1 quite easily DIY style. In a sense, the SD1 is just the younger bro to the later OD1. On the other hand, though there are much similarities, it is still a little more difficult to modify the SD1 into a earlier version OD1 with 14-pin op-amp. Main reason being that it is hard to get the 14-pin op-amp nowadays. Further, the SD1 circuit boards do not have the holes to accommodate the 14-pin op-amp. In a sense, the earlier OD1s are harder to come by, mod into, or cloned. So in this regard, if the RM800 OD1 is the later version one with 8-pins, then it probably is too pricey. From my experience, the later versions do not command such a high premium. They usually move at around 200-300 sgd depending on condition. But if the OD1 is the earlier version one, while RM800 isnt exactly a very low price, it is still within the range that I have frequently seen on ebay.
