you cant say in general whether the SE is easy to hack into a 9800/Pro. I dont know about the PCB of the Powercolor SE right now..it depends what layout the PCB is. Some SE cards are only 128 bit memory interface.... (the cards with the memory chips 'in line'). The other cards with the two mem chips on the side and two at the top ('L' type arrangement( are the ones with the 256 bit memory layout. (Like the 9800 Pro).
a) first...you need to be lucky to get one of these L-type memory boards to make sure you get the 256bit memory.
in addition
The SEs have 4 of the 8 pipelines disabled. The driver-HACK now tries to enable these 4 additional pipelines. But there is only a 50/50 chance that the 4 other pipes work (from whjat i heard) , if they dont (checker artifacts in benchmarks with the other 4 pipes open- ) then no hack can make these 4 pipes work because they're defunct.
If you're out of luck you spend $150 on a card with only 128bit bus and 4 not working pipes
If you're lucky you get a card with 256mem bus...and you can open/soft hack the 4 pipes....and then you have a 9800 Pro
Personallly, i'd stay away from the SEs...get a NP and flash to Pro
Edit: you might also wanna look at memory brand/timings. If it comes with some noname/infineon memory chips then dont expect clock rates like you can get with Samsung memory etc. Then you might not be able to reach Pro speeds and have to go lower.