PoS will not make Quark more inflationary. Currently Quark has a 0.5% inflation every year. We can split it as 0.25% PoW inflation and 0.25% PoS inflation. PoS will NOT kill Quark; instead, it will save it from attacks.

Network security is a very important issue, and PoS is an efficient way to solve this issue. With pure PoW, people has to set up miners to protect the network; given the very low block reward, a smart person doesn't want to mine Quark because the mining income can't even pay electricity. With PoW/PoS mixed, people can simply leave their wallets open to protect the network at a very low cost.

PoW coins with low/no block reward have been shown to not work. A recent failure is Coin2, which was under massive attack and had to implement PoS after that. The attacker even posted in the ANN thread and claimed that he earned 20+BTC by 51% attacks. Considering Coin2 only has a very small market cap, 20BTC is a huge number. Quark could be the next Coin2 if we blindly believe Quark is unique and shouldn't be changed in anyways, and don't take any measure to increase network security.

Low hashrate keeps investors away. Currently the hashrate is only about 400M. At this hashrate an investor is getting worried because one could lose his/her investment after a attack. This is definitely not good.

PoS is stronger than you think. I know recently there are some discussions on whether PoS is safe enough. Someone doubts if PoS provides enough protection. Yes, PoS could be attacked even only with 1% of the total coins, but it will happen ONLY IF very few people are connecting their wallets to the network and the active stake on the network is less than 1%. PoS can be 51% attacked if the attacker own more than 51% coin-age than the "active" coin-age on the network. We can simply encourage people to leave their wallets open when idle to increase the active stakes on the network to gain enough protection, much easier than encouraging people to fire up their equipment and burn electricity to mine. (Added on 05/31)However, implementing PoS and not asking people to open their wallets do not work. Coin2 is still a bad example here since it was said to be 51% attacked even after PoS implementation.

Price increase will not solve the security issue. If we do some good promotions and more people are buying (increase the price), the hashrate will go up as a result. Promotion is important; however, when the price goes up, attackers also have more incentive and are willing to pay more to do the attack since he can earn more after the attack. If price and hashrate increase at the same time with a similar scale, network security is not improved.