The PM-1's are excellent sounding bookshelf speakers, and yes, i do like them better than the LS50. They really do sound so nice! If you are planning to use a phantom center, the PM-1 would be optimal as they image better and have a more fresh & detailed sound, at least in my opinion.
The 75watt receiver is not going to cut it with either of these speakers because that power spec is probably over estimated anyway and being that the speakers are between 84db and 85db sensitivity you won't be able to go very loud without clipping and distorting the SQ.
My advise would be to get the PM-1's first, then save up for a good center channel, (a third PM-1 would be the best center channel option, I can't recommend the CM series as I do not believe that they are no where close to the PM-1's in sound quality) then save up for a new or used receiver and add a dedicated power amp to it. The cheap and easy way of doing this would be to buy an older used Yamaha RX-V663 for around $125 which supports the DDTrueHD and DTS-MA, and purchase a Behringer iNuke1000dsp for $185 and that would give you freaking awesome sound quality and the ability to use the Dsp in the amp to EQ the speakers to your room, all while giving you. 300 to 400 watts per channel.
Last, save up for a pair of good subs. I would suggest a pair of Dayton HO18's in a Stonehenge enclosure from DIYSG as they would crush ANY of the HSU's or SVS's for a fraction of the cost!