Well, having some 3Com 4800G, HP E4800, H3C S5500-EI, HP A5500-EI switches, I can happily report that you can throw every kind of SFP module at it and it will happily work, although it complains that the inserted modules are not H3C coded. Of course this is NOT guaranteed by anyone.
It doesn´t matter, so I could reuse all my e.g. Cisco, Foundry, Juniper, HP Procurve SFP modules which is simply great.
With, was it Release 2208?, there was actually a kind of problem where those ports have been shutdown a period of 30 days, but this was fixed with R2208P01 and R2210.
Hm, different optics for singlemode and multimode? What does the 4800 tell you, when you put them into the device? Are those recognized?